If you don't like the "4 men standing" analogy, how about your fridge, or a freezer? Load those up with food and if they're upright that's a very small footprint & a lot of weight that never moves. Couple that with the large adult that is constantly standing in front of the fridge choosing a snack and you've got even more weight. A water bed is another good example and the average weight is greater then 1,500lbs. Then tack on the weight of the couple sleeping on it and you're up to a good ton. Mind you, it's spread over a large area, but the weight is constant and therefore comparable.

For all of the threads I've read asking about the dangers of floors giving way, I've read none about it actually happening. I'm sure it does, but there's a lot of other things that happen much more frequently that people don't worry about.

I've got around 70 Gallons, and 100+ lbs of rock on a smallish footprint (4x2 foot). My house is around 100 years old with foundation problems, but the tank is fine.

LOL. I'm not smart enough to be an egineer but my boss is. I've learned to understand most of what they say. Take out all the big words, put together the small ones and you should get the just of what they say..

You should be good dude. I have a wood floor so I will be going out from an exterior wall with an added telepost underneath. And oh ya...... Insurance.

My friend & I were just discussing this topic the other day & I pointed out the fact that I have never read about or heard of an actual instance when a tank has come crashing through someone's floor. Neither has he.

Especially with a concrete floor, you should have nothing to worry about.

For every pound of live rock you put in it probly displaces about the same amount of water so the amount of rock or sand has very little impact on the final weight.

I just added "Renter's Insurance" to my insurance bill last week. Good call, TRIX :wink:

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 ;)

i live on the 3rd floor of a wood frame apartment, i have a 90gal tank, and no problem. i think you should be ok. it's not like your putting it in the middle of the room, there is more support at the walls, and you live in a concrete building so your fine.

In my humble opinion... okay maybe I should say the way I see it, a lot depends on how you distribute the weight. If you have the tank on a home made stand that has 4 1x4s as legs with nothing else supporting the weight you would want those legs to be on the supports under the floor rather than on a space between supports (trusses? maybe). If you have your legs in the 90 degree angle style... um like this "L" then you effectively cut the lbs per sq inch in half... (I think). If you build a stand that runs the legs down in the L patern then those are attached to more 1x4 or better yet 2x4 that run the length and width of the tank, with some 3/4 inch ply under them your weight is spread out over a very large area and I believe it would be supported in almost all situations. I'm not an engineer, I just remember the old analagy of a woman in a stilletto on your chest vs a sheet of plywood with some concrete on your chest the plywood wouldn't be as attractive but would be a lot more tollerable.

Doug

Well I have a 315 Gal system sitting in my kitchen do the math on that

One 265 Gal tank 500 lbs
stand Cap and sump 200 lbs
Live rock 250 lbs
Live sand 200 lbs
plumbing pumps and Mis. 150 lbs

and last but not least

315 gallons of water 3150 lbs

for a grand total of 4450 lbs

Yes 4450 pounds on a second floor I did reinforce the floor since the floor joist run the length of the tank so all the weight is sitting on 2 floor joist this is about the samr as standing a large family car on its end in the kitchen I was alittle nervous at first every time my cell phone rang while I was at work I would start sweating but one year later and still no problem