DannyBoy17
Fishaholic
I read osme of the posts about people with 6 seven tanks in a fish room, and they are deciding what filters they want for each tank. To tell you the truth, if I had more than 4 tanks in a room, what I would do is buy a nice big storage box, a few strong Powerheads, and some filter media, and I would create my own central system. You could have it so all the pumps for each of the tanks pump the water into the first section-> The water goes through a sponge and some floss. Next the water goes through an opening into a section filled with carbon and BioBalls. All of the water then trickles down into the third level, where return pumps pump the water back into the different aquariums. I bet this is a well know strategy, but it doesnt seem like many use it. Why not? You could even use gravity to return the water to the tanks if you have the sump at a higher level than all the tanks. 
Cheers.

Cheers.