Akaizhar

I've got a 7 gallon, wondering how many watts i should put over it?

SpeedEuphoria

depends on what plants you want to grow and if you use CO2 and ferts

Akaizhar

Yes, to CO2, yes to ferts, and maybe some dwarf hairgrass and some anubias

LordSul

I have an 8G with 2x24W PC lighting. With press CO2 and fertz.
As I recently learned, wpg rule does not work with small tanks. In my case I have 6wpg , you should probably look for similar values.