intersting article about all of this basically says "Yes, 4 250 lb men can stand in the same place at one time, even jump up and down - but having them there in the same spot for years causes a wear in the structural integrity that the floor was never designed for"
http://badmanstropicalfish.com/articles/article28.html
As I've been freaking out about this, seeing that on one side of my room I have currently 160g of water dispursed in a very, very odd way (tank stand that displaces the water upwards rather than lengthwise) and have approximately 100g sitting there plus another 60g next to it. Needless to say, it's a scary thought and I am seriously contemplating a move of some sort - however, if you look at the weight of a water bed (often 4000+ lbs) and the thought that these floors were designed for that - then there's another story entirely. And I think I like to use that to assure myself I'm not going to drown in fish poop
