I have a 20 long tank that I want to use for just corals. I need some suggestions for lighting. Right now I have 220watts of lighting that can be put on. My corals still don't seem to thrive. Salinity is at 1.023. This tank has been set up for 4 years. I have bubble algae and mushrooms and anemone's that thrive but no other corals. Any suggestions would be appreciated. Money is a factor as other people have to be able to keep these also. Otherwise what corals can thrive in smaller tanks with very little lighting? Thank You