Backyard Aquaponics
A place to discuss aquaponics

I am brain storming, but it does seem there are benefits in having an air tight container to do aquaponics in because, fish also produce carbon dioxide that plants consume.

Carbon dioxide injection (to air space) is commonly used in green-houses to boost plant growth. As Co2 is usually the limiting factor in plant growth. In intensive fish farming oxygen injection (to water) is used to maintain a large fish mass in relatively little water.

Circulating the gases is simple: a air stone in the fish tank water with the air pump in the plant chamber with the two chambers sealed air tight to each other. Could even use the air pressure to move the water??

Only problem i could foresee is tending to your crops without offsetting the co2/o2 ratio

Has any one done any studies of this type of inter action?

some info about the topic taken from
http://www.netpets.com/fish/reference/freshref/co2.html

CO2 concentration must exceed 30ppm before becoming dangerous to fish (although the pH drop caused by suddenly injecting this amount probably will).

At night, with the cessation of photosynthesis, plants become net producers of CO2 and consumers of O2 just like fish. This might lead you to believe that you should disconnect the CO2 at night to prevent CO2 building up. However the pH shifts caused by disconnecting the system will be much larger and more sudden than gradual change when the system is left connected.


Here's a simple equation to calculate CO2 if you know pH and KH.
CO2 = 3.0 * KH * 10^(7.00 - pH)
taken from http://aquaticconcepts.thekrib.com/Co2/index.htm

Burp! Toot! Burp! Toot!

(sorry)

I wonder if the Biosphere II project documentation could help answer that question - they were trying to keep from having to add any gases there, but eventually ended up having to add oxygen to keep the humans from expiring. Their plants weren't generating enough oxygen. Maybe the nitrification has an effect because the CO2 building up is what causes the water to become acidic?