I just bought a PHILIPS 20watt AQUA RELLA light. Can anyone tell me about it or what it does. It is the red packaging but there was also the yellow packaging, i wasn't sure what to get. I already have the blue. PLEASE HELP!!!!!
That is a general rule a lot of people use. The two biggest factors are probably the depth of the tank and what corals you'd like to keep. Hard corals and clams most likely need MH, whereas soft corals can be kept with PCs.