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.
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)!
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.
In the last post I noted some plants (especially Spinach) were exhibiting signs of iron deficiency. Iron deficiency is characterized by intraveinal chlorosis, which is yellowing of leaves between veins. Manganese deficiency can also result in this type of chlorosis, but in an AP system, iron is the primary culprit.
Spinach plants suffering from intraveinal chlorosis (two weeks ago):
Note how the veins remain dark green and the chlorosis affects only leafy material between veins.
As described previously, chelated iron was unavailable, so I experimented by mixing some molasses with a pile (about a tablespoon) of rust that had accumulated under a small pile of nails. There is absolutely no doubt that something in molasses binds iron. This has been documented by others (which is why I tried this). The rusty nails shed most of their rust after soaking in molasses for a few hours, and the rust itself appeared to go into solution. This mixture was then diluted in a liter of water and sprayed on plant leaves and at the base of the plants.
To make a long story short, this treatment did not work... at all - no ifs ands or buts. At least it did not work after a week of treatment. The plants basically looked the same as far as the chlorosis goes, and they were worse off in the sense that some leaves suffered from what I can only call "caked-on" molasses that formed dark, almost black spots on the leaves.
In any case, during the week I was very happy to find chelated iron locally. I also located seaweed extract, which besides containing iron, also contains a host of essential elements and unknown ingredients and which is known to be beneficial to plants. I applied these last week, and these are two of the Spinach plants as of yesterday:
There is no doubt they have "turned the corner". The dark brown/black spots are from the molasses. Some of the poorly damaged leaves fell off or were cut off, but not all of them. Some have recovered and no new leaves had developed chlorosis.
I moved some of the Spinach plants over to my new floating raft system, but left these two behind in the bath-tub grow bed. I somehow forgot to take pictures of the raft-plants this week, but will do so next time. The floating raft system is a post in itself that will be added shortly.
All in all, this has been very educational. I almost feel like I know something about plants! I highly recommend the two sites above on plant nutrition, and that anyone serious about growing their own plants learn basic plant biology and nutritional requirements.
And finally, some people apply molasses in a diluted form to ward off insects. The sweet smell repels many bugs for whatever reason. I used molasses for this reason when I first started my AP system and it did not cause the black spots it caused this time. This is probably just due to the dilution factor - I applied it too thick this time.
