Careful? Careful is what you tell your kid when you say don't run with scissors. You don't tell them to work with hazardous chemicals without protection of some sort.we run about 150 tanks off of one 100 gallon bio ball chamber, 6 UV sterilizers, 2 pumps, and a sand bed. I think it works fine, you just have to be careful what is going on in the tanks and watch out for diseases.