Sunday, July 6, 2008

Research

The Southern Regional Aquaculture Center has a good PDF on the UVI Aquaponics system.
SRAC Paper on the UVI Aquaponics System

I have some more results from the last batch of seedlings. Planted in rockwool, Tomatoes 100%, Corn 50%, and Oregano 10,000%, germinated and are growing well. The spinach, daisies, and sunflowers did not germinate. I transferred the seedlings to the dwc raft and terminated the remaining cubes. The seedling tray is out on the deck baking in the sun.

Lessons learned:
Algae grows on rockwool cubes.
Flies are really attracted to grow-lights. Then they drown in the plant water and it is icky.
Some plants, especially spinach, need different techniques to germinate.

That last point matches what I learned from the Cornell manuals on hydroponic production.

The links to the manuals are broken on the Cornell site, but I was able to find them with some google hacking.

Cornell Manual for Pak Choi Production
Cornell Manual for Spinach Production
Cornell Manual for Lettuce Production

In my other readings this week I learned a few more things. Commercial Hydroponics typically uses reverse-osmosis filtered water to eliminate buffering from the dissolved minerals.


I've been considering Ferrocement for the fish tanks. I think that the labor on that is going to be too much for me though, and purchasing a commercial tank or above ground pool remains a better option.

Here are some ferrocement resources
Building a FerroCement Water tank
a Youtube ferrocement tank video, much less "overbuilt" than the ones in the manuals
(removed dead link)

And finally, Catholic Relief Services Ferrocement Manual

It looks like the fundamental equation is managing the fish feed to hit the right nutrient levels for the plants. More fundamentally, balancing fish food and plant production. Everything else, Fish counts, DO, growbeds, rafts, etc, is just supporting the fundamental balance of fish food to plant production.

I replaced the grossly underpowered air pump in the dwc bed with a $20 Wal-mart air pump and a bubble wand. There was a significant amount of solids on the bottom of the DWC bed and the fish tank. I removed the inlet filter from the pump to try and help with this. Hopefully these two changes together will get the solids in the gravel bed where they belong.

The squash are showing tip burn. I'm going to point the fan at the beds tomorrow and see if that helps. The Cornell manual says that the tipburn is because of insufficient transpiration where the plants have nutrients and oxygen for a light level, but not CO2. Another balance. Light feeds respiration which requires nutrients, oxygen, co2, and water. With no greenhouse or shadecloth to manage the light levels, it is worth playing with the other variables to see what happens.

This is fun.
-ellie

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