DIY for a tank that small. Otherwise, you could go with the Fluval 20G kit. You can buy regular 16G refill cartridges for it for cheap. But that one works best if you turn it off at night to save CO2, which is not exactly automated...
Buy the GLC V3, it has standard North American Threads.GLA (cornelius) paintball regulator
I was talking about this one just to be clear:Buy the GLC V3, it has standard North American Threads.
The V2 only has Euro/Asian threads and won't ever fit CGA320 (standard North American Threads).
I have that set. It won't.