When I was in my early teens I had 12 in my bedroom on cinder blocks and 2 x's. 3 tiered stand. Raised some mouth brooders but mainly collected, breed and raised wild caught mollies. It was all to trade for enough supplies to keep the system going. My parents were very tolerant of all the gurgling. They were much more tolerant than the wife, that's why all but one tank stays at my shop.
3 in my bedroom. The 2.5 houses one red claw crab and isn't planted, though, and the 5.5 is as low tech as it gets. Really just a learning tank that I'm too lazy to redo. The 29 took some convincing before I was allowed that much water on the third floor. And it's taken up, by far, the most of my money and time.
I have 4 right now, but the 10 and 15H tanks are temporary. All of them are or will be ripariums. I have a 65 riparium set up as a display tank, and I'm now setting up a 45 gallon rimless tank as another display riparium. Ripariums Rock!!
I have 8 set up, some in storage in the basement. In the dining room a 72, 20 and two 10's, a 50 in the living room, a 10 in the kitchen, and a 75 and 55 in the bedroom. I'd have more but I'd have to sell the couch to make room and quit my job to come up with more time to tend them!