I have seven fish in a 63 gallon cube: Flam Angel, Coral Beauty, Blue Spot Jawfish, Yellowtail Damsel, Royal Gramma, and two Occelaris Clowns . I use tap water, and I do about a 5% WC once every three months or so. I also have zero algae problems, but do have to clean the glass once every few days. A 9X9" waterfall algae scrubber with about 600 GPH, an two 23W CFLs which keeps nitrates at ZERO. So everything was happy. I did notice that the water had a yellow/green tint to it. The skimmer addition took out the tint, and now my water is crystal clear.