I did have a setup 20H with 2 CFLs bulbs 23 watts - 6500k. I was successfull without CO2, then with diy CO2. Spent a lot of time errors/adjustement to find a right balance.
I am an amateur, according to me 3 CFLs without CO2 would be too much, but then it depends on the distance of the CFLs to the tank, and the lighting duration.
With diy CO2 i was lighting 8 hours a day, the bulbs were 8" over the water, was getting some filamentous algae that's all, and great growth.