A couple of days ago I went to an aquarium center and was inspired by there beautiful reef and fish aquariums. What shocked me was they used all artificial filters. No natural filtration except for some live rock in the 4 reef tanks. I asked the employee about it and all he said was " This is a pretty elite system. Elite? All they had was a UV. sterilizer, canister filter, protein skimmer, and I think they had an ozone generator. That’s what most of us keep in our home aquarium. This tank was at least 400 gallons to. It was strange to me because all the fish seemed healthy, there was not a trace of algae and this was a semi touch tank (they would take 5 specimens out and put them in a seporate bole just a bit above the 400 gallon's water level. After about an hour in that he would switch the specimens.) Wouldn’t that stress the fish and get them dirty. I now there are touch pools ware you stick your hand in the tank but thoughs tanks have extremely powerful filters.