Join Date: Aug 2015
Location: San Antonio, TX
Flexible CO2 system
So I believe I came up with a cheap way to make a CO2 system that can use many different CO2 sources: Yeast, Baking soda & vinegar, dry ice, or your own breath even.
I bought a cheap 2gallon garden pump sprayer. It has a max capacity of 45psi, with automatic pressure release if 45psi is surpassed. It uses an inline air regulator from harbor freight, inlet and outlet barbs from lowes, and a gang valve to fully shut off air flow without having to touch the finely tuned setting of the regulator. Total, it cost me about $28.
This setup allows you to pressurize your yeast mixture if needed, which brings in some fresh air at the same time. Yeast will eventually choke itself out if its environment is saturated with its own waste product, just like any other organism, so a small dose of outside air from a few pumps can't hurt.
It can also use baking soda and vinegar. This will pressurize itself so long as the top cap/pump is closed quickly after mixing. The same goes for dry ice which is pure solid CO2, however much more caution must be taken with it. Though there's an auto pressure release, I wouldn't max out often.
The final last resort option is your own breath. I read about air pumps and trash bags being used before, so the same idea applies here. Place pump in large trash bag, fill trash bag with breath, pump up spray bottle until high psi reached. Refill bag as needed. Personally, I don't think the co2 in your breath is as significant as you think, so this might be an option for borderline low tech tanks only.
Let me know if anyone else has tried something similar. I would love to know if I'm just being hopeful with this. Not sure how long it should last if fully pressurized and running for only 8-10hrs a day at 1bps. I've only done some rudamentary math on volume/psi.