The other thing that you can do is have each tank with its own sponge filter and then a central water change system. In this type of system each tank has its own sponge filter so you don’t have to worry about the possibility of spreading diseases. It is also plumbed for a water overflow system (there are a couple of different types some you drill the tank others you don’t).
Jim Graham has a great set up. This link shows his fish house in progress. http://www.motorcityaquariumsociety.c ... USE/dream_fish_house.html
I will have to venture over and take some pictures of the finished room as I don’t see any online. It is very impressive and he has taken time to think about everything.
Jim has a central air system. Each tank has a wall type sponge filter on it. He also has each tank plumbed with an overflow. The last piece is every tank is plumbed so that he can do a central water change. When new water is added to a tank the overflow allows the water to drain away.
With this type of a set up there is no contamination, you can use sponge filters and water changes are easy.
Most people with fish rooms find that heating the room is easier and cheaper than heating each individual tank.
I hope this helps.