[nalu86]

If you add co2 you will have to find a balance between nutrients, light and co2.
for co2 you shout at 30ppm, if you have surface agitation going your fish shouldn't have a problem with the co2.

look into diy co2 to try it out.

If you want to go the pressurized co2 way, I would say, research and read, read and read some more and then have a big wallet ready. I spend months researching it before I tried it.