DIY CO2 for a 75 gallon tank
So I want to build a DIY CO2 system for a 75 gallon I've started up and really have no idea what I'm doing. I was thinking about using three 2 liter bottles and attaching one tube to all three using T-connector. Then just run the tube into the tank and let it go. What are the check valves used for? I guess I hook the end into an air stone however I've never used air stones and know nothing about them or what type to use. Am I on the right track? or am I missing something completely? Any help given would be greatly appreciated.