Super Pedro:
As you are the only person i know of using Co2 in a micro environment i would like to pick your brain on the subject if you don't mind.
how did you quantify whats being used by the plant and how much to replenish it by.. This is what i always found as the most important piece of information. I know you use an air tight box under water to meter the amount to flood the room with, but the needle valve that you use to "top it off" in between flooding cycles is what interests me most. How do you measure the level and know the precise amount in there with out say a sentinel or some type of Co2 PPM instrument?
Well. I have no way of doing measurements as I grow along. I'd love that, but I can't bring my self to use 1000$+ on my micro cab(GF agrees on that ). But I'm hoping to buy a cheap monitor one day.
When I did my first grow in the aero system, I borrowed a measuring device from work, at took reading at the intense early flowering.
Basically, what I did was to time how fast the plants were at bringing the CO2 level down from 1500 to 1300 ppm. Then I did a calculation of the needed flow rate to counter that.
By using the "submersed upside-down measuring cup" technique I adjusted the flow, monitored a full cycle, and made sure the level dropped a little bit in between the dump. So they receive to much when they are small, and to little when they are big - but only by a few hundred ppm's.
Anyway- Helping the Calvin cycle with access to more CO2 isn't the only gain from using it.
I can control my temp and Rh to perfection. A lot of people don't realize how important optimal climate is for the metabolism and the yield of the grow.
Cheers