A spare bedroom in our house has been converted into a fishroom. Situated directly across the hall from a bathroom, and with a window into the fenced back yard near one of the shallow ponds, I have ready access to water and no problems with discharge. The walls were painted and the floor as well with a garage floor paint, which was then sealed. We put a commercial grade cove base around the bottoms of the walls and sealed it with silicone to help prevent structural damage in the event of an overflow. A dehumidifier is necessary as nearly all the tanks are uncovered at the moment, but that helps keep the water temperature where it needs to be.
Most of the lighting has been hung from the shelf above, which makes access to the tanks much easier. Right now we are running hang-on-back filters and air (sponge filters) by way of several small air pumps. Ultimately, we will convert to all air using a single linear pump, and switch to uniform energy-efficient lighting. Glass will need to be cut to cover the tanks with two overlapping panes for temperature and humidity control. Most of the tanks have come out of our larger utility fishroom in another building and have massive hard water drip stains. We are chipping away at them with a razor blade whenever we get a chance.
We have added a 4′ double stand designed for two 55 gallon tanks in front of the large window and have put two 20 highs on each shelf. In addition to this, we added a smaller shelving unit by the closet door that serves as sort of a work station / herp table. Prince Charming, the dumpy tree frog, lives in his tank on the top shelf along with a plant jar (with shrimp) and a tiny 2 1/2 gallon tank that houses a Betta. Underneath that is the brine shrimp hatchery and the lighting for the turtle tank on the bottom shelf, which is home to a little mud turtle named Kinsu and a couple of fish that he decided to make friends with rather than eat. He is my excess snail disposal, and provides endless entertainment for the cats when the Ancistrus on the bottom row of the other racks aren’t out eating.