The Unfortunate Reality of Lettuce Bolting(!); Cool Lessons in Reducing Nitrate Levels to Induce Fruit Setting

Wow, well it's been 3 weeks since I updated the blog. Unfortunately, there have been some set backs. My lettuce production streak came to a screaming halt, but at least I can say it does not have to do with the aquaponics system.

We basically had some horrible weather, which is to be expected at this time of year. From the time of the last update 3 weeks ago, it literally rained non-stop for the following two weeks, so there was very little to no sun. As a result, all the lettuce in the raft beds bolted. A plant "bolts" when it is under stress - i.e., under unfavorable conditions. In the case of lettuce, the result is the plant stretches up, becoming spindly, and develops an unpleasant taste. The leaves stay small, and become elongated. After that, the plants (at least in this case), do not grow very much, if at all.

As a result, last week I threw all the lettuce out (54 plants) and replaced it with new starters. Unfortunately, those starters were purchased an entire week before planting, and during that week, the starters were also in really bad weather. They were not showing signs of stress or bolting when I transplanted them to the raft beds, but this weekend, one week into planting, they do not look very good. I think they have just about all bolted. Not having any new starters to replace them with, I left them in the raft beds this weekend. I will take new starters next week and will restock if need be.

    Weekly aquaponics system update; showing lettuce that has bolted due to

prolonged bad weather, and needs to be thrown out.

In the meantime, the cucumber and tomato plants, all growing in gravel beds, are showing tremendous green leafy growth. Unfortunately, they are not setting fruit. The cukes set, but then fall off before they develop. The tomato plants don't even get that far - no fruit setting at all.

The good news is, I think I know the solution. The other good news is the plants look fantastic. If I do succeed in inducing fruit production, the plants should be able to hold plenty of weight.

I went over my UVI course notes, because I remembered there is a key part of their system they regulate in order to achieve better fruit set. Sure enough, in, Recirculating Aquaculture Tank Production Systems: Aquaponics—Integrating Fish and Plant Cultureby James E. Rakocy, Michael P. Masser and Thomas M. Losordo, Southern Regional Aquaculture Center Publication No. 454, we learn that:

The accumulation of too much nitrate in aquaponic systems is sometimes a concern as fruiting plants set less fruit and produce excess vegetative growth when nitrate levels are high. The filter tanks in the UVI commercial-scale system have a mechanism for controlling nitrate levels through denitrification, the reduction of nitrate ions to nitrogen gas by anaerobic bacteria. Large quantities of organic matter accumulate on the orchard netting between cleanings. Denitrification occurs in anaerobic pockets that develop in the sludge. Water moves through the accumulated sludge, which provides good contact between nitrate ions and denitrifying bacteria. The frequency of cleaning the netting regulates the degree of denitrification. When the netting is cleaned often (e.g., twice per week), sludge accumulation and denitrification are minimized, which leads to an increase in nitrate concentrations. When the netting is cleaned less often (e.g., once per week), sludge accumulation and denitrification are maximized, which leads to a decrease in nitrate levels. Nitrate nitrogen levels can be regulated within a range of 1 to 100 mg/L or more. High nitrate concentrations promote the growth of leafy green vegetables, while low nitrate concentrations promote fruit development in vegetables such as tomatoes.

I should have known those darn nitrate levels were the problem since I spent so much time discussing them and trying to get them down! Anyway, mystery solved (hopefully).

In order to incorporate a mineralization section in the system, I set up the old blue barrel again. Only this time, instead of functioning as a swirl filter, it is going to function as a mineralization area. The barrel receives fish tank water through a 3 inch pipe that enters the barrel from above and does not end until it is almost flush with the bottom of the barrel. Then, greenhouse saran is stuffed in the barrel, in a circular fashion all the way to the top, where the drain pipe is. The drain pipe empties into the system sump, and from there it is pumped to the grow beds and to the fish tank. There is no centrifugal action in this set up.  The netting prevents the water from forming any kind of a lateral current.  The water is just pushed across the multiple layers of saran so that as many deposits as possible are left on the saran.

The saran will catch all sorts of solids which will serve as growing areas for anaerobic bacteria. These will denitrify nitrate to produce nitrogen gas, as described by Rakocy above. I have no idea how long this should take. I am guessing 1-2 weeks, and am very excited to see if I get positive results.

I wanted to know what concentration of nitrate one should aim for, exactly, and so I contacted one of the professors at UVI. The answer is 20-40ppm, which is about a tenth of where my nitrate levels were a week ago, and about half of what they are now. However, I think the reason for the sudden drop has to do with an inadvertent partial water change that took place upon incorporating the mineralization tank (a story for another day).

So that's the update for today. That covers the last three weeks. Hopefully there is better news coming soon with some good tomato and cuke production (as well as lettuce)! Actually, I will be very interested to see how lettuce does with the reduced nitrate levels, as what's good for fruiting plants is not optimal for leafy greens. That makes me want to have two systems...

Video showing set up of mineralization tank designed to host anaerobic bacteria. 
The anaerobic bacteria reduce nitrate to nitrogen gas, and therebye reduce nitrate
levels in aquaponics system.  Lower nitrate levels are desired for fruiting plants to
set fruit.  Skip to 1:50 for the mineralization tank discussion.

Lessons in Water Chemistry Part III; Phone a Friend; and Resumption of Fish Feeding

Since last week marked a full month since I last fed the fish, I decided to seek some expert advice on the nitrate levels (and fish feeding). Back in March I attended the University of the Virgin Islands International Aquaponics and Aquaculture Course. The course is taught by Dr. James Rakocy, who is responsible for most of the work leading to aquaponics as we know it today, and his staff at UVI. Although Jim has retired from UVI, he came back this year to teach most of the week-long course, along with his staff members, Charlie Schultz and Don Bailey. Dr. Wilson Lennard, whose work I sited in a previous blog, also participated by giving a lecture via a remote link-up to Australia.  

In any case, I wrote a quick note to Don Bailey, to see what he thought of the high nitrate levels. Don and the rest of the UVI team are professional scientists, growing tens of thousands of pounds of fish and vegetables annually, using aquaponics, year in and year out, so I value their opinions, to say the least. After he scolded me for starving the fish (sorry Don!), he said nitrate levels are safe up to 500 mg/liter. That's the same as 500 ppm (parts per million). He also said I definitely have a secondary source of ammonia, given that the fish had not eaten for an entire month and that nitrate was still present.

The only obvious source for that ammonia which later gets converted to nitrate, is fish waste and other waste (plant roots, leaves, and other material) trapped in the gravel grow beds. It is likely that the red composting worms are responsible for turning that waste into ammonia, which then gets converted by bacteria into nitrate. The ammonia measurements I took of red composting worm leach ate, which came in very high, support that thesis.

As a result of this interaction, we started feeding the fish again last Tuesday. We started them on a very light diet (1/4 of what they normally got for 2 days, and then 1/2 as much as what they were getting previously), as I was afraid of giving them too much after so much time without food. Also, because of the secondary source of ammonia, I want to make sure I do not add so much food that nitrate levels shoot up beyond the 500ppm level. As a matter of fact, I may leave the feed level at around this rate, or even reduce it, depending on nitrate levels.

Again, my goal is not to grow tons of fish. I am more interested in plant production. Therefore, my goal is to maintain nitrate levels that will result in the maximum amount of plant growth, without maxing out on fish feed and fish growth. I believe that if there is a way to accomplish this, it is by saving fish waste and letting it decompose over time in the gravel grow beds, assisted by red composting worms, rather than by removing it from the system (as is done at UVI and most other places).

In my measurements today, nitrate clocked in at between 100-200ppm. The particular kit I have maxes out at 160ppm, so I took a second reading of a 1:10 dilution for more accuracy, and came up with the 100-200ppm reading that way.

Here's the video for the week.  Besides the water chemistry discussed above, there is also an update on the plants, including cucumbers, tomatos, and lettuce.

Click here if the video does not play.

PS:  I harvested 6 fully-grown lettuce heads today!  Next week I should have a near raft-full (18) of lettuce ready to take out.  It's getting to be time to upgrade the system.  I'd like to be cranking out 100-200 lettuce heads a week, and have room for other stuff.

Oct. 2, 2011 Review of Plant Growth a Month Into Starving Fish; More Lettuce Harvesting

There is not a whole lot to report this week. I harvested 24 fully grown lettuce heads this week plus 3-4 not-so-fully grown ones. This is becoming a regular occurrence now, which is oddly disappointing. I guess the novelty is gone!

As far as water chemistry goes, nitrate levels continue to hover near the high end of the scale, clocking in at between 40-80ppm. Because of that, I am continuing to starve the fish. They have now gone an entire month without any fish feed being thrown in.

I am getting a little worried about approaching the limits here, but I am told Tilapia can go a "winter" without food. I don't know where I read that or what that even means. Tilapia are tropical fish, so what winter would they even be talking about?

Anyway, I'll have to do some more digging around, but I am not too worried. Fish are cold blooded, do not have to maintain any kind of internal temperature, and since they float in water, there isn't much energy used in keeping themselves "up" as it were. They use food for growth only, not for maintenance. Based on that set of facts, I suppose everything should be OK.

The plants continue to grow like gangbusters, and already one of the cuke plants is flowering. It's been in three weeks since planting. Truly amazing, in my book!

Here's the video update for the week:

click here if video does not play

Lessons in Water Chemistry Part II, Request for New iPad App

Well, it's been three weeks since the fish last ate.  Amazingly enough, nitrate levels are still through the roof!  But, they are no longer off the scale.  Yesterday's nitrate levels measured between 40-80ppm.  Three weeks ago they were 80-160ppm, or higher (off the scale). 

As would be expected, plant growth does not  appear affected by the diminishment in fish feed.  That's because of the residual nitrate in the system (see Part I). 

The exception is with the lettuce heads, which have not grown as quickly.  The only explanations I can think of are:

These are different lettuce plants, genetically. I doubt that's the case, but it's a possibility.  The lettuce starters come from the store and so I have no control or knowledge of whether or when they change seed lots.  Still, lettuce seeds are bought or produced by the thousands - no, 100's of thousands by any starter-producer, so I highly doubt I happened to catch the "switchover" to a new batch or breed, and even if that were the case, I doubt one kind of lettuce is going to grow that much more slowly than another.

More likely, the difference has to do with some potassium I added to the system two weeks ago.  Potassium or calcium should be added periodically because these are usually lacking in fish feed.  Also, the nitrification process lowers the pH, slowly over time.  Either potassium or calcium (in potassium hydroxide or calcium hydroxide forms) can be added the raise the pH, and since they are essential for plant growth and missing in fish feed, they are convenient to use because they will not kill the plants or build up over time.  As a result of the potassium I added, the pH went from about 6.6 to about 7.2 or 7.4.  That's much more of a swing than I expected or wanted at one time, so I'll add much less next time.  By the way, this pH swing was caused by adding a mere 2 tablespoons of KOH to a 4,400 liter system!  

But anyway, I am making a big deal out of relatively nothing.  The lettuce heads did grow, just not as quickly as past batches.  In the meantime, everything else is growing like gangbusters. 

Tomato plants that were barely 7 inches tall 3 weeks ago are now 40 inches tall.  Their stalks went from sphagetti thin to well over "pencil"-thick.  Cucumber plants, in the system 2 weeks, easilly doubled, if not tripled, in size. 

You can compare the size of everything in the video below (compared to last weeks video):

click here if video doesn't play

Fish starvation will continue until nitrate levels come down.  Hopefully that won't be more than another week or so. 

The interesting thing about all this is that it shows that aquaponics can be used on a much less intense fish-farming level than is widely assumed, or at least than was assumed by me!  For those more interested in plant production and not so much in fish production, that is very important, moreso if one is trying to produce food commercially.  Fish feed is one of the major input costs in commercial aquaponics.  After electricity to run water and air pumps, it is the #1 cost in most places. 

If fish waste solids can be recycled in the system rather thrown out, then the fish feed necessary to grow plants can be reduced, along with costs.  Red composting worms play a key role in role in this.  I doubt it could be possible otherwise.

Obviously, there are a whole lot of people that have spent a lot more time studying all this than I, but based on limited but real results, I say it's worth looking into some more.  I've gotten here by mistake, and I have possibly endangered my fish by subjecting them to high and extended periods of nitrate levels.  But the principal appears sound - namely that solid fish waste can be kept in a system that includes gravel-based beds innoculated with red composting worms, where it will be processed by the worms and reduce the amount of fish feed necessary to grow plants.   Some balance between the amount of gravel-based beds (worm habitat volume), worm density, fish density, steady feed rates (unlike mine!) and plant growing area must exist.  Isn't there an App for that?

Here's another video, this one more about the plants than water chemistry.  Also some nice flowers at the end.

click here if video does not play

Lessons in Water Chemistry

The Problem:

I think I mentioned last week that nitrate levels were high.  Well, after not feeding the fish for a week, they are still way too darn high!

High nitrate levels won't harm fish right away, but over an extended period of time, they can be dangerous and even fatal to fish.  How high they have to be and for how long in order to kill fish, I have no idea (and it probably depends on the fish species), but with the nitrate level almost off the scale, I felt the need to do something about it.  As a result, we stopped feeding the fish 6 days ago. Amazingly enough, after 6 days of zero fish food, nitrate levels are still through the roof!

Water Chemistry in Aquaponics Systems

For those new to or just getting started with aquaponics, now may be a good time to review just what is going on in an aquaponics system, on a basic chemical level.  There is no need to review any formulas or know any formulas, but you should understand the basic process and what makes it work, and specifically, the following:

1. Fish excrete ammonia in their waste and through their gills
2. One type of bacteria converts amonnia into nitrite
3. Another type of bacteria converts nitrite into nitrate
4. Both these bacteria are ubiquitous in the environment.  They will naturally come to flourish as long as ammonia is present (no need to add them to an AP system)
5. Nitrate is plant food and is consumed by plants in aquaponics systems.  This step completes the process of removing what would otherwise be toxic ammonia produced by fish from the water in a way that is beneficial to other organisms - plants, all while recycling the same water in the system.  One way to look at it is, fish produce plant food, and plants produce clean fish water.

In a balanced aquaponics system, ammonia, nitrite, and nitrate levels should be low.  This is because ammonia is quickly converted into nitrate and nitrate is consumed by the plants. 

Stop Feeding Fish - The First Solution to Almost All AP System Problems!

High nitrate levels generally mean not enough plants are present in the system.  I've added plants to my system, but it will be some time before those plants get large enough to consume the quantity of nitrate I suspect needs to be consumed in order for nitrate levels to come down. 

In addition to adding plants, and because nitrate levels were so high, I also stopped feeding the fish entirely.  For anyone worried about fish not eating, thinking they'll starve or something like that, I highly recommend this video by biologist and aquaponics expert Dr. Wilson Lennard.  Skip to about the 2 minute mark for his remarks on feeding fish and you'll see why it's the least of my worries.

By not feeding the fish, the system (through the plants) must consume all available nitrate at the same time that no new nitrate is produced.  That is what should happen.  That is why I am surprised that nitrate levels are still as high as they are (160 ppm - no change from last week).

Theories, Conclusions and Squirly Friends

My current (and only) theory as to why this could be is that inside my gravel grow beds, there are significant amounts of fish waste, and plant roots and other plant debris, from the 10 months or so that the system has been active.  All of that material is continuously decomposing via much of the same processes involved in the convertion of ammonia into nitrate.  Certainly, the fish waste that accumulates in there follows the same process, and other organic waste (such as plants roots) eventually also break down into something that enters the nitrogen cycle and also winds up as nitrate, eventually. 

One factor that could influence all this is the presence of red composting worms added in May of this year and later in June.  The reason these could be having an influence is because after their addition, all that accumulated waste should break down more quickly.  That of course is my assumption and I have no way of proving it.  On the other hand, composting worms are used the world over precisely because they accelerate the composting of organic waste, so it would be pretty silly to think otherwise.

So basically, what I am imagining is that although there is no longer any food being added to the system, nitrate is still being produced via the same nitrogen cycle pathway but using accumulated waste still in the gravel beds instead of "fresh" ammonia produced by fish.  I suspect red composting worms may be playing a large role in the process.

Speaking of our worm friends, here is one of the ones we found today after we dug out the strawberry plants.  They were definietly NOT this big when we added them, so yes, they must be eating something, and they must like it!

Another theory I had, but which I dicarded today, was that worm leachate added over the past week was somehow spiking nitrate levels.
Let me back up first:  besides the worms present in my gravel grow beds, I also have a worm "farm" set up in some plastic bins.  This is NOT a part of my AP system.  It is just a red composting worm farm where I compost vegetable waste.  My system consists of two bins - a lower bin and an upper bin.  The upper bin is where all the food waste goes, and is where the worms are.  The bottom of that bin has some holes drilled into it so liquid can drain into the lower bin.  If you are interested in setting up something like this, I highly recommend this red worm composting site, which is where I got started. 

Being new to red worm composting and not really understanding what is meant by "worm tea", I thought that the liquid which falls into the bottom bin is what is meant by "worm tea".  It turns out this is not worm tea - it is considerd "leachate" and is not recommended for adding to plants except in very diluted quantities.

I did not know this of course, until today, when I finally discovered what worm tea really is.

Before discovering this, I added 500 ml of worm leachate over the course of the last week.  Today, I measured nitrate, nitrite, and ammonia levels in the leachate.  As you'll see in the video, nitrate and nitrite were not detectable, but ammonia levels were very high (50-100ppm).  Obviously, this ammonia would quickly be converted into nitrate upon entering a system where the bacteria necessary for the conversion, like an AP system, are readilly present.  However, the amounts of ammonia added (500 milliliters of leachate), compared to the total volume of my system (4,200 liters), simply do not explain the level of nitrate seen. 

To summarize, the only conclusion I am left with is that some source of ammonia is being converted into nitrate in my AP system.  Since the fish are not being fed, the only source of ammonia present must be accumulated waste from 10 months of running the system.  Since worms were only added after 7 months of running the system, there could very well be lots of waste and tied-up nutrients in the gravel beds that is now currently being released.

The good news in all of this is that it could mean that these systems are possible to run using less feed than is commonly used, especially compared to systems where almost all of the non-soluble fish waste is removed via filters, and in cases where the emphasis is on plant production, not fish production.

My system has two filters - a clarifier, and a "pad" filter.  However, the material that accumulates in the clarifier filter is NOT discarded.  It is dumped into one of the gravel grow beds so it can be decomposed by worms.  The reason it is taken out by the clarifier filter only to be dumped back in the system is so that it does not accumulate in the sump.  Once it is in the gravel beds, which are essentially giant filters themselves, I have little worries about it re-entering the system without decomposing and dissolving first.  The material that is caught by the "pad" filter is thrown away, but only because there is no easy way we have found to get it off the filter pads and into the gravel grow beds very easilly. Otherwise, I'd recycle that, too.  The "pad" filter only filters the portion of water that enters the floating raft portion of the set up.

I have noticed some people with AP systems try much too hard to keep everything clean and filter the heck out of their water.  This is especially true of people with hydroponics backgrounds.  The nice thing about aquaponics is that you can get pretty damn messy and not worry so much about keeping things "clean".  "Dirty", in a biological system/environment to me means something that cannot be eaten (builds up as waste which can become toxic) or that causes desease.  In an aquaponics system, it turns out, almost everything can be and is eaten!  As for desease-causing organisms, of course desease can occur in these systems, but it is much less likely to break out because there are so many natural antagonists present in the form of competeing organisms. 

Below is the video version of most of what's above.  It is waaay longer than I expected/planned, so my apologies.  The point of these blogs posts and videos isn't solely to drive you into a comma! ;)

They are also for me to keep track of what I am doing and thinking, and they are fun to do.  Thanks for reading/watching.

More Lettuce Harvesting Madness(!); New Tomato Plants; Worm Tea

Well, I was able to harvest 33 awesome butterhead lettuces today!  New lettuces were planted as soon as those were taken out.  I also made room in the two larger gravel beds for new plants, and started by adding 7 yellow tomato plants today.  More plants will follow in the coming weeks.  I'll post video updates on those tomato plants in some sort of organized fashion so that growth rates and quality can be appreciated.

Click on this link if the video below doesn't play. 

 

 

Here are the lettuces loaded onto the back of my truck. This is totally smaller than small potatoes, but it still feels great to be able to produce your own food. 

Floating Lettuce Rafts Day 21

If video doesn't play, try this link.

Tarragon grown in floating raft system

Adding Liquid Chelated Iron to Aquaponics System

Click here if video does not play.

Lettuce Raft 6th Day Update

Phenomenal growth so far!

Replanting of Raft Beds After 4 Weeks of Autopilot

It's been a heck of a time since I posted any updates. That's because I was away on vacation for 3 weeks, and then even after I got back, it's taken a while to get back in the "swing" of things.

The time off served as a good test for the system. Sure, my caretaker watched after it, feeding the fish and taking water measurements. And he threw plants out that were stricken with disease. Maybe it was more of a good test for me! Normally, I can't wait to get back to the farm every weekend to check on things. This is a good thing, but it's also important to have enough confidence in the system and the person watching after it to be able to let go for a while.

All the tomato plants that were in the floating raft beds had to be thrown out. Apparently, they were afflicted by the same black, filmy, bugs that took out my watermelons a month or so ago. The same thing happened to the eggplants.

The floating rafts were proving tricky for the growth of tomato plants anyway. The roots were so developed they were clogging the flow of water from one bed to the other. That's because the floating beds are only connected via a 1" or so pipe and there is almost nothing I can do about that and keep these particular beds.

I will only grow lettuce and other not-so-large plants in them going forward. Tomato plants will have to go into the gravel beds or whicking beds for now on.

I brought the level of fish feed down to 1/2 the normal amount in the last two weeks, due to all the plants that had been taken out. I am bumping that back up to normal now that I have the floating rafts planted again.

I don't have any plans for the vertical grow towers at this point. I obviously need a stronger pump and I don't feel like making that investment right now!

I replanted the rafts beds with lettuce this weekend.
The first video below was taken the day I returned to the farm. The second video shows the planting of lettuce plants in the raft beds yesterday. It shows how to remove the starters from nursery trays, how to wash them and how to place them in the raft beds. Obviosuly, there are many different ways of doing these things, and different people have different "tricks" they use.  Would be interested to know how other people do these things.



If the first video doesn't play, click here.



If  the second video doesn't play, click here.

Pipe Change-Out, 5,000 or so additional (legal) workers, Vertical Tower Build (and semi-fail!)

I decided to change the pipes out, again.  Yes, this is the second time.  I used 1/2" PVC in my first build.  Then I upgraded to a 1" o.d. irrigation pipe (3/4" i.d.) to increase the flow.  That was a huge improvement, but it was nothing compared to the latest upgrade to a 1-1/2" i.d. pipe.  That's a big pipe, and the flow rate is awesome!  The pump manufacturer for the pump (it's a Danner mag-drive "12") recommends 1-1/2" as a minimum to achieve the flow rates they publish, which is why I decided on this size.  I do not know the exact formula, but I am fairly certain that flow rates are proportional to the square of the radius of the pipe, so going from 3/4" to 1-1/2" should result in about 4X the flow, all else being equal (which it probably isn't). 

In any case, the increased flow rate keeps the fish tank water much much cleaner.  That also means there are a whole lot more particles making it to my gravel grow beds, where they can be mineralized, rather than staying floating around my tank, where I am not so sure what happens to them biologically and chemically speaking. 

Here's a vid describing the change-out where you can also see the puurdy new pipes and fittings, and appreciate the super-duper water flow(!):

Also new this week are 5,000 (could be 1,500 or 10,000 or 8,000 - I really couldn't say) new workers and they all fit in the picture below.  This is the latest addition of our amazing friends, eisenia Fetida.  I had added red worms to the system a few weeks (month?) ago, but I also set up some Red Composting Worm bins at home and at the farm with the same batch, so I was a little short with what I added to the beds.  Also, upon reading that they take 60 days to double in population, and being as impatient as I am, I decided to add more the easy way - buying more. 

These were added at night simply by placing them on top of the gravel beds. They moved in and under the gravel fairly quickly.  From what I have read about these worms, aquaponics gravel grow beds should provide near-ideal conditions for these organisms. 

The purpose of adding these to AP systems is so they assist in breaking down organic solids left in the beds.  This mostly consists of undissolved fish waste particles but there are also plant roots, dead leaves and ocassionally fruit that falls off and does not get picked up.  The gut of these worms contains several times more bacteria per volume than their surrounding environment (I read somewhere 13X more) and those bacteria are able to digest a myriad of organic components, some of which we may not even know of or yet understand.  Their metabolization of these compounds releases simpler compounds or elements back into the system - many of which can then be used by the plants.  Red Worm compost and Red Worm compost tea are valuable fertilizers and there is actually a market for them where farmers pay good money for them.  These worms will be producing the same compost and tea right in the grow beds, 24X7 in what is probably very close to an ideal environment for them.  I recently also read that Will Allen at Growing Power, uses red worms in huge quanitities in their systems. 

Finally, as mentioned in the video above, I began to set up two vertical grow towers above one of the gravel grow beds.  These take great advantage of vertical space and my goal is to grow strawberries with these systems.  That in fact was one of the main reasons for changing the pipes out.  I got the towers built, and if you want to see how they are put together, see the video below.  Unfortunately, I still cannot get water up to the top of the towers!  That was a slight dissapointment, and I'll have to figure out a solution.  The towers are nice though, and I can't wait to get them working!

Clarifier Set Up, and End of Times Plant Update

As promised, below is a short video which hopefully explains the new clarifier set up.

To summarize, the original clarifier was a swirl filter.  It was made out of a 55 gallon barrel mostly buried in the ground.  It worked fairly well in terms of trapping heavy particles (i.e., negatively buoyant particles) but I had no way of easily cleaning it.  The only way to clean it was by temporarily pumping the water out and then scooping the sludge off the bottom.  This was very time consuming, and inefficient.

In order to be able to clean it properly, the barrel should be cone-bottomed with a drain line attached.  I have not been able to find any cone-bottomed barrels of a suitable size.  There are some for sale that I could attach a drain line to, but they are much too large for my system, and I don't even think they'd easily fit in the space I have available.

This is the smallest available cone-bottomed barrel I could find.  It holds 303 gallons and measures 1.16 meters across - much too large!!

I don't even want to think of the sized hole that would have to be dug to incorporate this thing.

Because of all this, and looking for something smaller, I decided to try and use a reconfigured 5 gallon jug, like the kind that go on those water fountains:

Placed upside down and cutting the bottom off, these have a built-in cone and an easy way to plumb a drain line in.  I took one of these jugs, cut it in half, and drew the profile out on a piece of rubber (in this case an old dog house):

I then took a second jug, cut the bottom off, and inserted the divider down the middle.  It was glued in place using Duretan.  I clamped a hose onto the neck and attached a PVC drain line onto that, and then buried the jug from the cone-down into the ground.

The result can be seen in the video below:

This thing works OK so far.  Maybe I will like it better with time.  I am not 100% convinced right now but it is definitely better than the prior set up with the unclean-able barrel.

As for the plants, they're doing well, especially since the world didn't end on Saturday.  Here's an update:

Gone Fishin'

I decided to take some fish out of the system this weekend.  The reasons for this are because a) the fish are ready to eat (that should suffice!) b) I have plenty of smaller fish in the system which actually grow faster and process more food by weight than the big fish, and c) I am actually worried about creating an overpopulation problem which could lead to system-wide collapse/death eventually.  Granted, that would still be a few months off.

I'm only talking about three of the largest fish, mind you!  There will be plenty left afterwards. 

I lowered the water in the fish tank by moving as much as possible into the gravel beds, the raft beds, and into the sump.  I set up a small but functional purge tank in an old fridge.  Fish go in the purge tank for a few days (recommended is no less than 4) with no food.  This results in tastier meat. 

The videos below show the various steps involved, and three nice sized Tilapia in the purge tank at the end!  This was a little more difficult than anticipated!  I will have to get better nets for this in the future.

As for my swirl filter, I will update that next week.  I put together a sort of clarifier using a 5-gallon water bottle.  I cannot say yet if it works or not.  It appears to be too short because there is just not enough head created by the jug to force the solids out like they should be.  It does collect solids and I am able to take them out, but it is far from optimal.  If I could only find the exact same thing but 5x bigger!

The Good, the Bad, and the Ugly

Sunday, May 1^st, 2011:  The Good, the Bad and the Ugly 

Lots to update this week.  I'd been away for two weeks except for a very quick visit last weekend that didn’t really allow me much time to look at everything closely.

The Good:

On the Good side of things, almost all the plants are doing great.  The video all the way at the bottom of this update shows all the plants.  The watermelon bed, which hosts two watermelon plants, has growth all over the place.  The bed itself is not even visible anymore.  The plants have made their way onto the fish tank cover and the floor and there are more watermelons coming out.  On the other hand, the watermelons themselves appear to grow quickly at first but then the growth rate tapers off.  None of the watermelons are ready and the largest ones do not appear to be growing much anymore if at all.  Maybe this is normal, I really don’t know.  I'll have to read up on watermelon plants.

On the Bad side, the watermelon plants are suffering from some sort of infestation.  I noticed this started last week, but I wasn’t here long enough to even think about what to do about it.  There is some sort of white/tan-colored, very small bug sticking to the leaves.  They do not move unless you disturb them.  They do not appear to eat the leaves.  By that, I mean they do not leave behind leaves with holes in them.  They do leave behind a black, very ugly looking film.  Maybe they suck nutrients out of the leaves without leaving holes, but what do I know?  The strange thing is, the leaves don't look unhealthy, other than having that sludgy film on them.

Here are the bugs and the film left on the leaves:

Upper Right Corner:  White/Tan colored bugs visible.  Almost Everywhere Else:  Black film left behind by bugs. 

Click on the image for a better view.

In any case, for lack of any better ideas, I sprayed the plants down with a molasses solution (just a 1-liter spray bottle of water with about ¼ cup molasses and a squirt of dish soap mixed in).  Some bugs are repelled by sweat smells so maybe this will work.  While spraying the leaves, I noticed the black film they left behind washed off pretty easily, so if the molasses doesn’t work, maybe a good spraying with the hose will get them and their trash on their way!

Almost all the plants planted last week seem to be doing well, with the exception of a single yellow-tomato plant in the gravel bed, which appears to be rotting at the base.  This is what ultimately afflicted all the tomato plants that had grown in that bed previously, so that’s disappointing.  I’ll keep an eye on the other tomato plants in that bed and watch out for the same symptoms. 

The tomato plants in the raft bed are doin’ great.  I wish I had taken pictures of the roots.  That will have to wait ‘till next time.  I filled the rest of that raft bed (raft bed 1) with other tomato plant types: cherry, roma, and more yellow tomatoes.  If they all flourish, that’s going to be one hell of a bed! 

Yellow Tomato Plants.  I planted other tomato plants in the rest of this raft (not shown). 

Background:  Half-barrel cemetary from original design.  I still might get some use out of those, so there they sit until needed. 

In raft bed two, I planted new lettuces (shown in video).  I bought the starters at the store.  In raft bed three, the mustard plants are goin’ crazy, as can be seen here:

Worms:  When I first learned about aquaponics, one of the key components presented was worms that would grow (and must grow) in the gravel grow beds.  Worms play a key role in decomposing fish and plant waste that accumulates in the gravel grow beds.  Worms both take advantage of this material and release the minerals therein for plant use, and also keep the gravel beds free from clogging.

What I never saw discussed anywhere was which kind of worms to use or where to get them.  Little did I know that mattered!  The first time I tried adding worms, I just dug around in the ground until I found some and placed them in my gravel grow beds.  A few weeks later, hoping to find worms slithering all over my beds, I was highly disappointed to find not one!  The ones I’d added died or escaped.

As it turns out, not all worms are equal – far from it!  The type of worm that is best suited for decomposing waste and is used the world over for composting, is Eisenia fetida.  That’s the scientific name for California red crawlers.  Or in Europe, Eisenia hortensis.  They thrive in rich organic matter, can tolerate high temperatures, and can withstand the flood portion of the flood and drain cycle without a hitch.  These are the worms used in composting systems, vermiculture, vermicomposting, and it’s what those guys I first read about doing gravel-bed aquaponics use.  However, it seems that in some places these worms will just crawl out of the ground and into your grow beds all by themselves.  Maybe that’s how it works in Australia, which is where most of the aquaponics stuff I first read about takes place, but not here!  In most places you will probably need to find someone that harvests these worms and buy them.  That’s what I did. 

And here they are:

They burry themselves in the soil, so you have to disturb the surface in order to get any kind of a
picture of them, of which this one is, I just realized, quite lousy.

I set up what is in effect an “inoculating nest” on top of each bed today.  The nest is just a small plastic plant container (with those big drain holes on the bottom resting on the gravel bed) filled with worms and the material (worm compost) they come in, and covered with another plant container upside down (with the holes up, providing air).  I am hoping they will make their way into the cool, dark, moist, oxygen rich, and waste-rich beds underneath.  If they don’t, I will be incredibly disappointed to say the least.  I thought I learned something here, so don’t let me down, my red, wiggly, friends.

This is a great site with just about all the information you could possibly ever want on red composting worms:  Red Worm Composting. The worms make great home composting systems too of course.  I set up two this weekend – one for the house and one for the farm. 

The UGLY:

My swirl filter has gone anaerobic, no doubt about it.  This gunk floating on top, pictured in the last update, reeks.

It does not appear to be affecting anything (yet).  From the swirl filter, water drains to the sump, where it is heavily aerated.  I think the nasty gases produced by anaerobic minerilization get fairly well vented out in the sump.  They certainly do not appear to be harming anything at this point.  Anyway, I have a plan to tackle this but haven’t had the time to implement it yet.  Basically, a better designed solids-capturing system that can be cleaned regularly I think will do the trick.  The current swirl filter is just not easy to clean, so things that collect overstay their welcome and go anaerobic.  I do think this waste can go into a nice vermicomposting system later on – something else to research. 

This week's video update:

Lettuce Raft Production in 25 Days; New Vertical Stacking Component

The plants are looking fantastic, and are growing at a good clip too.  The lettuce seen below went in on March 25th - that's 25 days ago.  Not all of them are ready to harvest, but 9 of 15 are.  The others I think will take another 2-5 days, depending on which particular head we're talking about. 

At UVI, in their fully-optimized system developed over a span of 30 years, they get full lettuce heads in about 21 days, so this isn't a bad second-trial.  That's more a testament to how easy aquaponics is than to anything special about my system. 

Below are two vertical grow towers I just installed on top of one of my gravel grow beds .  They're designed for strawberries and are made by a company called VertiGrow out of Florida:

The pots stack one above the other and are filled with support media.  I will pump my fish water up into the highest one. The water will percolate down to the next pot through holes at the bottom of the first, and eventually through the other pots and into the gravel grow bed.  I am hoping to use these for strawberries, although it is hard to find starters here.  If not, I'll have to come up with something else to grow in them, which really shouldn't be hard.  They are a great use of vertical space.  They provide 4 planting spots per container - one per corner, so each one of these towers can hold 20 plants.  That's more than each of my floating rafts. 

My fish have multiplied and grown quite a bit since I started.  That was 6 months ago with 5 adult fish.  I have no idea how many fish I have now.  There are easilly more than 60 and quite likely over 100 at different stages of growth.  This is actually a horrible way to keep fish, as I learned at UVI.  The correct way entails separating the females from the males, keeping separate brood stock, and managing stocks of fish at similar growth points.  I won't get into details here, because doing so is really an entire aquaculture course in itself.  Suffice to say that is is very important to grow out a portion of your total capacity in controlled, timed, amounts, and to maintain your line's genetic purity by keeping separate brood stock.  I may change my system drastically down the road and actually produce fish the correct way.  For now, I'll just continue with what I've got, knowing it is not the most efficient way to do so.  It does suffice for a home-based system of this small size.  The fish are doing great at their main job, which is to produce plant food.

One of the problems with all the fish growth is that my swirl filter appears to be having "issues":

That's floating fish gunk, fortunately not making it down the exit funnel and into the rest of the system.  I am not sure why it is floating.  It shouldn't be.  It should be settling at the bottom of the swirl filter where it can be scooped out later.  In any case, it isn't, and it's time I change this filter system out for something easier to clean, so I'll be focusing on that in the near future. 

And here's a quick video update of all this.  If it doesn't appear below, click on this link:

Weekly Video Update

Lettuce is looking good - no bolting!  Zuccini plant is ginormous, but no full grown zucs yet.

Back on the ranch... er... farm, literally. 3 weekly video updates.

Well, it's been a quiet several weeks. I attended the UVI International Aquaponics & Aquaculture course in mid March and have been back 3 weeks.

Here are my notes from March 25, which was my first day back at the farm since my last entry:

AP system notes

ph readings show 6.8 consistently
Plants are mixed. Some are pale, some are green.  A lettuce I did not have much hope for went to seed but also was richly green.  Fed it to the fish.

Chemicals:

Based on the UVI Aquaponics system, I added chelated iron to 2 mg/liter.  This took 250ml of my liquid chelated iron solution.

Added 1/2 teaspoon of Potassium.  Based it on instructions on package of 1-2 kilos per hectare and proportioned it down.

Applied a foliar spray of potassium.  Diluted 5 ml into 2 liters and applied to leaves. Dumped unsprayed amount into system at mineralization tank.  

Note:  on my phone instructions, Carlitos added a tuna-tin sized amount of builder's lye to the system last week, for bringing calcium up.  Though the fish feed already has some, UVI says add more.   

I'll check ph first thing tomorrow.  It may go up do to the K and Ca.

Planted chives, 16 lettuces (starters purhased at store - yes I cheated), cilantro, parsley, celery, one medium sized chile plant.  Threw out most or all of the brocoli started  2 weeks ago.  I don't think those plants would have made it in any system really.  Divided the chives and cilantro between gravel and raft systems.  All the letuce went into the raft sysem.  Everything else went into gravel.

Almost everything greened up right away after adding the iron, calcium and potassium. The only thing that didn't were two watermelon plants in the raft system. The ones panted in gravel did react positively.

The following are three video updates, about a week apart each. Each video goes from plant to plant in the same order. You should be able to notice plant growth and other differences from video to video.

March 26:



April 2



April 8

Tomato Leaf Curling Virus, or Something Else? Wicking bed and watermelon success; floating raft trials.

The tomato bed has 5 tomato plants and two cucumber plants (and various herbs).  Three of the tomato plants produce cherry tomatoes, one is "yellow" (produces a small, completely yellow, and deliciously juicy tomato) and one produces a variety that I can best describe as "normal".  Of the three cherry tomato plants, one developed severe upwardly curled leaves all over the plant, pretty much "overnight" (though I am not 100% sure on that score since I didn't see it the day before). They are not only severely upwardly curled, but are also "collapsed" at the part where the leaf meets the stem.  The plant basically looks god-awful, no if's and's or but's.  The fruit however, doesn't look bad, except a lot of it has ripened pre-maturely.  Instead of "cherry" tomatoes, some of these are "red pea" tomatoes.  If you google "tomato leaf curl"  pictures, you'll see some that show a slight curl and some that show the leaf completely closed in on itself.  Mine are the completely closed in kind. 

In researching what this could be, I came up with two possibilities:

1)  Nutrient Deficiency
2)  Disease

I've ruled out #1 because it seems to make sense that anything caused by a nutrient deficiency would also affect the other plants, especially other plants of the same type - i.e., tomatoes.  In Aquaponics and hydroponics systems, all plants receive the same nutrient mix, all the time, so it just does not make sense to me for just one plant (out of a group of the same type) to suffer nutrient deficiency.  If anyone knows something to the contrary in this regard, do please let me know!

As for possibility #2, what I have been able to find is there is such a thing as Leaf Curl Virus, which can be transmitted by beatles, aphids, and other leaf-eating bugs.  It will not spread from plant to plant by contact or via the roots - it requires a leaf-sucking insect "vector" to transmit the disease.  For lack of other possibilities, and following the philosophy of "the simplest explanation is usually right", this is what I think affected this plant.

If so, this would be the best possible reason, given the circumstances.  Nutrient deficiency would mean something is severely lacking or unbalanced in my system, whereas this particular virus, which thankfully cannot spread very easily, can be taken care of by removing the plant.  There are no signs of aphids or leaf-eating bugs though, so I cannot be 100% sure.  Stems of affected plants appear healthy.  There is no discoloration inside stems that are cut open for inspection, that would indicate a fungal or root-born disease.   

Now, if any other plants come down with this, I'll have to go back and question my reasoning here, but for now, that's all I can conclude.

The radishes in wicking bed #1 are doing great.  It looks like they'll be ready to eat in a week or two.  I planted red onion and carrots in the larger wicking bed, as well as thee asparagus crowns I had planted in a dirt garden. 

The floating raft pots are 100% planted now (all 54 of them).  Beds 2 and 3 are full of brocoli, mustard, sweet peppers, and watermelon.  I am very doubtful as to the brocoli and mustard as the plants looked weak, long and spindly, but we'll see.  I've been surprised by how well some plants do when they are moved into an aquaponics system.  Raft 1 has everything I had planted before (lettuce, cabbage, spinach) plus I added three new yellow tomato plants.  Those yellow tomatoes are just too tasty and I want more of them.

Here's some video of this week's progress.  I spent a little too much time on the seed trays, especially since they were mostly a failure, so be forewarned!  The seed tray part is from the 49-second mark  to 3.26 if you want to skip ahead.

Fresh Pickin's

Here's what we picked off the plants this weekend:

Those yellow globes are yellow tomatoes.  They are new for me and I have never seen them at the grocery store here.  They are much smaller than regular tomatoes, stay yellow just like in the pic, and are much juicier and sweeter than regular tomatoes.

There is not a whole lot to report this week.  The tomato plants and cuke plant look good and are producing.  The watermelon and zucchini plants look like they're taking well to the system.  The spinach and lettuce are not looking good - nothing new there.  The spinach is looking yellow again as is some of the lettuce.  I added more liquid chelated iron (4%) this weekend.  All together, I've added an estimated 1/2 a 500ml bottle of liquid 4% chelated iron to the system. 

PH is holding steady at 6.8.  Last weekend it shot up to 7.0 for no reason I can think of.  After adding three cap fulls of phosphoric acid, it got back down to 6.8.  PH is tested daily, so any kind of iron lockout due to high PH is highly unlikely. 

I changed my pumps out today and replaced them with a Danner mag drive (magnetic-drive) pump.  The difference in efficiency will pay for the pump in two months.  Here's a video explaining the change-out, and then pics of the pump specs.

The small wicking bed is looking good.  These are baby (right) and regular (left) radishes after 3 weeks of trans-planting.  Large wicking bed hasn't been planted yet.

Cherry Tomatoes

Here are some pictures of the cherry tomatoes and cucumber plant. They're a better representation of the plants than the video I posted earlier.

Feb 20, 2011

Youtube Video update, February 20, 2011. Great cherry tomatoe production, cuke plant beginning to produce (and has grown to roof!), whicking beds set up.

I'll have more on the whicking beds in a later post, and I'll also feature an improved germination method I've learned from Carlitos (Carlitos's Way, I've coined it)!

Floating Raft System

I've finally added floating rafts to my aquaponics system - pics and video below.

The basic setup consists of three 525-liter capacity beds, each with a fitted styrofoam sheet on top with holes for 18 plants on each raft:



Water is continually pumped from the Sump (CHOP Mark II setup) to the fish tank, the two large gravel grow beds and to the floating raft system. The fish tank is fitted with an overflow pipe that continuously sends water through to to a Swirl Filter, and from there to the Sump.

Water pumped from the Sump to the raft system travels through a Matala pond filter to remove suspended solids prior to entering the raft system. Water exiting the raft system and the gravel grow beds, returns to the sump.

If video does not appear above, paste this address into your address bar: http://www.youtube.com/watch?v=DE9BNYMSSD0&feature=youtube_gdata_player

Although gravel grow bed systems do not need particle filtration (they are the filter), raft systems do. This is because in raft-ponics, plant roots are submerged in water 100% of the time, making them perfect landing places for suspended solids, which fish produce large quantities of. Without proper filtration, suspended solids will cover and eventually suffocate the plants.

The Swirl filter in place between the fish tank and the sump will do a good job of settling out heavy solids. By heavy, that means anything that will sink - i.e., not neutrally buoyant. Neutrally buoyant particles (suspended solids), need to be filtered out another way

The particulate filter comes straight from Matala, which builds these for pond filters. It is of course possible to build your own, but the filter sheets come in very large and inconvenient sizes, and I would never have any need for all that filter material. The cost of this purpose-built box with the filters was cheaper than building one on my own, at least with a Matala-type filter. The possible downside is these are designed for ponds of at least 10,000 gallons, so my system is waaaaay over designed in this area. I only want to keep adding onto the system, so I do not see this as a waste, and the shear convenience of getting something ready made and practically "plug and play" was totally worth it in this case.








I started the first two rafts off with lettuce, brocoli, and spinach. The letts and brocs came out of the germination tray they had sprouted in about 3 weeks ago, so I am skeptical they will do that well. I have some new plants getting to planting stage soon that I will transplant in the next few days into the remaining raft and possibly into the others if the plants in those don't look like they're improving.

Raft-ponics is supposed to be the best method for growing lettuce, so I am very much looking forward to seeing how this all works.

My system right now contains quite a large water volume compared to the amount of fish. My tank, which will be able to hold 130-160 fish, is 1,700 liters (450 gallons). The total system volume is about 4,500 liters (1,200 gallons), when you add in the new floating raft beds. This should add a great deal to system stability in all things pH, temperature, and chemical balance, but my guess is that the water has to be pumped through the cycle quite a few times to get the same amount of plant nutrient to the plants. That shouldn't be a problem once my fish grow and populate the tank, but for now it may lead to some slow (but steady) growth. We'll see.

I will be taking the University of the Virgin Islands International Aquaponics and Aquaculture Course next month and will not be making any more significant changes until after completing the course.