Don't know anything about CO2. Substrate in all my tanks is just rocks but that can change.
Tank 1
5 Gallon Hex
Heater
Bio-Filter
Incandescent Light
When It finishes cycleing it will have 2 ADFs and thats it.
Tank 2
10 Gallon
Heater
Bio-Filter
Florescent light
4 Neon Tetras
2 Black Neon Tetras (will add one whe I fix the over crowding problem)
2 Clown Loaches (Moving to a 20 Gallon when it's cycled)
1 Glass Fish (moving to 20 with a friend or two)
1 Peppered cory (getting some friends when overcrowding is fixed)
1 ADF (going to 5)
Tank 3
20 Gallon
Heater
Bio-filter
Florescent light
Air pump
2 Clown loaches from 10
some glass fish
I'd like to get a little vegitation in all the tanks, but not so much that I become a horticulturist or any thing.