Tuesday, November 2, 2010

Think Twice Before Feeding Your Fish Chicken Shit, and Other Mysteries.

Today I had the rare opportunity to visit the farm and my AP system during the week. I had to pick up Tora, a Malinois half-breed 10-month "pup", and bring her into town to get her fixed.

As I posted last week, I was surprised to find my nitrate levels were through the roof. I was initially very pleased to see this, until I began to really think about why this shouldn't be possible. Also, a full 30% of my readers (Ready), commented about how this was likely due to something other than the presence of nitrogen fixing bacteria. He suggested the chicken waste, which in an earlier post I had indicated was likely to be in my gravel, was the likely culprit. If so, and if more chicken waste was being somehow added to the system, this could pose a serious problem.

Well, as it turns out, someone (me) had suggested to my caretaker, Carlitos, that Tilapia were such hardy fish they could eat anything, even chicken shit. Well, sure enough, Carlitos took me up on my suggestion and was feeding them a few pellets per day (four to be exact). Mystery solved!

Now, even with this gross introduction of nitrate to the system, nitrate levels were down today compared to last Saturday and Sunday. When I added the extra bed, I also added more water to the system, so that obviously helped. The good news is that nitrite levels are now detectable, as seen in this nitrite and nitrate test:

Those nitrite levels were not detectable in my weekend test. So, some bacteria has apparently started to make itself evident.

Other than chicken-poop, we were feeding the fish dead bugs and dog-food pellets. The dog food pellets did not prove very popular, but they did eat them, grudgingly. Both of these ideas were spawned by my desire to avoid buying fish food, and by wishful thinking that I'd get my own fish-food supply system going soon (duckweed or worms). Well, today's realization and experiences led me to go straight to the agro supply store and pick up real fish food:

That's 14 kilos for about $22. Enough to feed my existing fish for a very very long time. Of course, I'll be adding more fish very soon. The fish loved the pellets. Of course, after a week of dog food and chicken shit, who wouldn't?

My other "mystery" revolves around my PH levels. The water I used to fill my tank comes from a natural spring. Its PH is around 7.0-7.2. The water in my system, for whatever reason, is at PH 8.0. JAG suggested I check my gravel. I did so by filling a small container with natural-spring water and checking the PH before and after adding gravel. After letting the gravel sit in the water since Sunday to today, the PH is at 8.0, so sure enough, it's the gravel.

I am not quite sure what to do about this at this point. Changing the gravel is a huge proposition and I am hopeful I can get the PH down over time. Maybe hope is not a good strategy. I have read of systems going from 8.0 down into the preferred 6-7 range over time, but I do not know if their high PH situation was caused by gravel or something else.

For now, I am content to wait, watch, and see how the plants behave. The ones I planted in the bath-tub appear OK. One, a jalapeno plant, I took out of a planter because it looked like it was drying out and getting ready to die. Since being in the AP system, it has recovered significantly.

The Jalapeno plant is the big one on the left. Everything else is basil (mostly), one cantaloupe, and there are two asparagus crown I took out of my dirt garden and am testing here.

I went to the nursery last night, picked up plants for the other bed, and planted them today:

That's Carlitos in the background. Here's a close-up of the plants:

I installed these laundry baskets in the tank today in preparation for hopefully getting more fingerlings this weekend. They're meant to provide shelter for fingerlings - a place the can be away from the big fish. I don't know if this is really necessary or not, but it seems like a good idea I got off Murray Hallam's site.

And here is Tora, who made today's progress possible:


  1. I've always heard that the stuff that is bad for you is what tastes the best, so maybe chicken shit fish will be a delicasy.

  2. Ready, I'll let you know. Maybe it will replace caviar. A man who has never made a mistake, is a man who has never done anything. Yeah, I'll just keep repeating that line to myself until I feel better!

  3. Damn...so it is the gravel....that sucks. I spoke with my father (a Professor of Inorganic Chemistry at the University of Houston) and asked him if there was anything you could mix into the gravel to buffer the alkalinity of the limestone, but he had no solutions applicable to a gardening system.
    I'm afraid there is no option than to replace the gravel, as the plants are going to starve growing in this media. He also said both the acidifying action of the bacteria's nitrification process and any exogenous acidic buffer wouldn't stand a chance against the mole-load of the limestone gravel.
    I'm sorry buddy, I wish I had better news. Look for gravel that is rounded pebbles of a silica-quartz type content. It might be a good idea to test a small purchase to be sure it is pH neutral before buying in bulk. I think know of a local supplier of hydroton expanded clay pebbles. Worst case scenario, you could purchase some when your here over X-mas and have it shipped.
    Let me know if I can help....sorry again for the bad news....Jeff

  4. Farmer,

    I have to second Jeff here. I've been doing a lot of building around here, and I have gotten several loads of both river rock, as well as "Chert" rock, which is essentially limestone that still has quite a bit of lime powder in it. We use the chert for a base for pouring concrete, because it packs up so nice. The river rock was used in places where we walk, on the edges of the new lake we put in, etc. It is completely different, and is rounded without sharp edges at all. I guess that is from the erosion. Chert looks excactly like what you have in your beds, except the stuff I get still has powder in it. Yours looks like washed chert.

    What a major bummer. The bad part is, the more acid you put in the water, the more the limestone is going to buffer the PH by disolving.

    Here in the US I can get a truckload of 6 yards of river rock (which is way more than you need by the looks of it) for $180. Hopefully you can find something like that in CR.

  5. JAG/Ready: Thanks for the info. For the moment, there is nothing I can do anyway. Tropical strom Thomas has washed out roads and bridges all over the country. My normal route to the farm will be closed for a while - major bridge is just gone. My alt route take about 45 minutes more, but I won't be able to go this weekend, at least not for long enough to do a gravel change. I think what I'm going to do is set up two more beds with new gravel, so I have a place to transfer my plants from the old beds to when I switch those out. In the meantime, I'll let the system run as is and see what happends.

  6. Sorry to hear about the storm, sounds like it did an incredible amount of damage. Good idea about adding additional grow beds, but it sounds like you have more pressing matters to deal with.

  7. JAG/Ready: Could the high PH (we're talking 8.4 at this point) prevent plants from absorbing/processing nitrate? I ask because my nitrate levels are through the roof again. I changed 1/2 the water last Tuesday (almost a week). Nitrates were down to about 30ppm after that change. Yesterday, they were about the same. Today, Carlitos called to tell me the test came out deep red - which is in the 80-160ppm range. Of course, I don't know what Carlitos means by "red", but if he's right, my nitrate levels are out of control. I instructed him to change 1/2 the water. In the meantime, I'm making progress on replacing the gravel. I bought my sifting screens today and will hopefully have screen-boxes made before I go to the farm Friday. The stones taken from the river are still fine - PH is still at 6.2, so I think we're good to go with it.

  8. the pH can affect the availability of nutrients in the soil.
    Many nutrient cations such as zinc (Zn2+), aluminium (Al3+), iron (Fe2+), copper (Cu2+), cobalt (Co2+), and manganese (Mn2+) are soluble and available for uptake by plants below pH 5.0.pH levels also affect the complex interactions among soil chemicals. Phosphorus (P) for example requires a pH between 6.0 and 7.0 and becomes chemically immobile outside this range, forming insoluble compounds with iron (Fe) and aluminium (Al) in acid soils and with calcium (Ca) in calcareous soils.Soil acidity is reduced by volatilization and denitrification of nitrogen. Under flooded conditions, the soil pH value increases. In addition, the following nitrate fertilizers — calcium nitrate, magnesium nitrate, potassium nitrate and sodium nitrate — also increase the soil pH value.Many plant diseases are caused or exacerbated by extremes of pH, sometimes because this makes essential nutrients unavailable to crops or because the soil itself is unhealthy (see above). For example, chlorosis of leaf vegetables and potato scab occur in overly alkaline conditions, and acidic soils can cause clubroot in brassicas.A pH level of around 6.3-6.8 is also the optimum range preferred by most soil bacteria, although fungi, molds, and anaerobic bacteria have a broader tolerance and tend to multiply at lower pH values. Therefore, more acidic soils tend to be susceptible to souring and putrefaction, rather than undergoing the sweet decay processes associated with a healthy, living soil.

    In order to remove nitrates, the plants need to grow - become physically bigger, which locks it up in the leaves, etc. If your plants growth is being stunted due to high PH, the nitrate reducing properties also decrease. If your plants are dying, it will actually increase the nitrates. Delicate balance and all.

    Water changes seem to be your best bet until you can get back there.

  9. That above post (top part) was supposed to be a snip and a link, but somehow that formatting got removed upon posting.

    The point I was trying to make is that high PH can stop the plants from taking in any nutrients, including nitrates, if the plants are either not growing or dying.