you will need a good skimmer..... and also depends on what kind of fish you have..... I have 3 skunk clowns, 3 perc's, blenny,skipper, 6-line wrasse, mandrine, flame angel, koran angel, naso-tang, coral beauty, hermits(blues,reds,bumble bee) pepermint shrimp, cleaner shrimp, 2 seabae and 3 long tentacle anenamee's, turbo snails. 70 lbs.live rock all in a 55 gallon..... with a emperior filter, skilter 400 and a fluval 402........