[andsoitgoes]

The problem with looking at things like a fridge, bathtub, washer, etc is that when the house was designed, the engineers knew "Hey, this is where the fridgei s going to go" and planned for the extra weight.

I'm guessing they didn't look at the bedroom and said "Hmm, this person might just put over 1000 lbs of water here. Let's do some super reinforcement of the floors"

As for the rock displacement, it doesn't fully displace the same amount of water, the link above has a bit of a calculation as to how that works - because of the space the rock itself occupies. Here's an explanation:

"I added 210 pounds of rock to my aquarium so now my aquarium setup weighs 210 pounds more."

• In the above example, when you added the 210 lbs of rock it took up space that was previously occupied by approximately 1.5 cubic feet of water. So you've really only added 116 lbs (the "buoyant rock weight") to the total weight.

Again, like Seahorse_Fanatic said, it's something that's talked about but is never something that anyone has actually heard of. On the same note, so is a heater exploding and turning your entire tank into very expensive soup, it's just a matter of how much risk are you willing to take.

-- and saying that, I'm planning on doubling my home insurance policy