I know it is so hard to have just one tank, I started out with one 2g hex, than I added a 10 and a 29g, I was good for awhile but I wanted bigger tanks, so I sold those and got a 55g, but then I say a bookshelf aquarium I just had to have and then finally added my 75, but I am still constantly checking out craigslist for any great deals on aquariums. I too have gone around and measured vacant spots in the house. But I am trying very hard to limit myself on just three tanks. But I wouldn't mind a pond...hmm...