Join Date: Dec 2014
Location: Panama City, Fl
To prevent the yeast mixture from entering the tank, the tubing should be routed into another bottle of equal or greater size, and then on to the diffuser in the tank. This allows for any overflow to be captured. I once had a DIY C02 system get knocked over by a curious 1 year old, while I did not suffer any losses the tank was very cloudy when I got home. No one likes doing multiple 100% water changes... It is my understanding that the sugar/yeast can/will cause a fungal breakout. I did not experience this because I flushed the system pretty good. It is also my understanding that use can dose H2o2 in the event of your mixture being injected into the tank to help.
As for the benefits/drawbacks, They can be a very cheap answer to the question "should I dose Co2?" That is pretty much the only benefit. On the downside, they are only effective on smaller tanks without doing multiple bottles. You have no control over how much your dosing, and you cannot just turn them off. I am sure you can incorporate a needle valve in the tubing to adjust down the flow rate, however you're running the chance of blowing your bottles or tubing up, leaving your place smelling of cheap beer. Another drawback being the smell of the fermentation process.
I would run it on tanks up to 20 gallons, after that I would seriously take a look at a pressurized system such as the Aquatek Mini Co2 regulator on a paintball canister, at $100 set up its a "cheaper" Co2 system, and is what I just purchased to run my 5.5 gallon. It has a solenoid incorporated into its design so it can be set it up on a timer to ensure you do not overdose.