Steady Supply of DIY CO2
Hi Brian,
Since, I believe you are using DIY CO2; one of the main issues is maintaining a steady supply.
A trick; is to use two generators, I use two-liter soda bottles run into a single container, I use 500 ml Erlenmeyer flasks, with rubber stopper, check valves off each generator.
I use about 300 ml of deionized (DI) water in the bottom of the flasks with the two inputs, three sixteenth inch rigid air tubing, extending to just above the bottom of the flask. The output extends slightly below the stopper. For the flexible tubing, in keeping with my “on the cheap” philosophy I use black quarter inch drip irrigation hose. I have been using this tubing and various drip irrigation parts in my aquaria and ponds for almost ten years.
I have found this arrangement works quite well up to 70 gallons or so, I currently use this system on a heavily planted 55-gallon tank that I use for experimental purposes. Primarily, I suppose, because I was told it could not be done, I have been operating this tank for over five years. By simply alternating replacing one bio generator at each water change, the drop checkers (I keep 3-6 in this tank to monitor CO2 disbursal) indicate 30ppm, I am now able to measure with greater (calibrated, even) accuracy and it seems to be quite stable at 33-35ppm CO2.
For diffusion, I have found a simple counter-flow device, with strong circulation to be adequate. I use an old gravel vacuum, like six by one-and-a-half inch cylinder.
The output from the flask, to just above the rim of gravel vacuum, I use a small fitting for drip irrigation, and then a water pump placed at the opposite end of the tank, the same side as the intake for the canister filter, with the return to the top of the gravel vacuum.
Because, I am, well me,
I developed pressure release valve at the top of the gravel vacuum to adjust the amount of CO2 dissolved into the water.
Those of you with your beady light-adapted eyes, a brain and opposable thumbs, would do well just to drill a few holes at various levels down the cylinder and plug whichever of the upper ones as you wish to contain more CO2.
Instead of ruining gravel vacuums and such, I recommend those View-Tainers, I read about around here. I can’t believe I didn’t think of abusing something like that.
Biollante