weight of a tank

Considering the slope on the 33 gallon, I would not try a 150 gallon on that floor.

1500# for a 150 gallon tank is guessing it a bit high since water weighs a little over 8# per gallon, but when you're trying to figure out if your floor will support it, guessing high isn't a bad thing to do at all!
Your other tank not being level doesn't necessarily mean your floor is weak, just, well...not level. I knew I'd have that problem when I set up my 29 gallon years ago in a very old house, so I tried shimming it from underneath but it still wasn't perfect. If you don't care about that, your fish won't either, hehe.

A 150 gallon is a whole nother ball of wax, though. That much weight could cause problems if your floor can't handle it. Is the basement going to be comfortable for you and the fish if you put it down there? Not too cold? A comfy place to sit and watch the fish? An easy to reach water source?

If you really want it upstairs, have you thought of shoring up the floor from underneath with some 4x4's? If how it looks in the basement isn't a concern, that might be an option to help make things safer.

Checking with a local builder might give you some good ideas and answers.

I'm setting up a 185 in a few months and have to reinforce the floor under my house.
Its a rancher style (one level) and theres a crawl space underneath where i'm going to make a cement foundation and some support columns.

According to All-Glass your filled tank will weigh in a 1800 lbs. I think they take into consideration gravel weight.

The floor not being level really isn't a concern unless it's way out. The stand can be shimmed to an extent. What kind of stand is it? If it's a metal stand it'll be a lot easier as you will only have to shim under the legs. I'd strongly recommend using oak shims as the weight will destroy pine, rubber/plastic, etc. Metal stands exert extreme psi's on the floor because usually it's just the bottom edge of the leg (angle iron) making contact with the floor.

If it's a wood stand, usually more material is making contact with the floor so I'd suggest taking your stand to a finish carpenter to be shimmed properly. If you could get the carpenter to do this at your house it'll make things a whole lot easier.

The flooring and orientation of the floor joists is of extreme importance. You want a sub-floor/floor setup. The floor joists should be perpendicular to the direction of the tank. In other words, when facing your tank the joists should be running from the wall behind the tank to the wall behind you. You want to spread that weight over as many joists as possible. Unfortunately if your stand is metal you will probably have problems spreading the load over several joists.

Wood stand usually = harder to shim but better at distributing the load evenly.
Metal stand usually = easier to shim but tougher to distribute the load evenly.


Do not underestimate the weight of that tank! Like others suggested, a builder could give you the best advise.