Will my 2nd floor support a 90-125 gallon fish tank ?

Hi guys,

The goal of what I’m trying to accomplish is to keep a 90-125 gallon fish tank on a second floor, of a townhouse. (Built in the early 80’s) There is no basement to be able to view the direction of the floor joist, which leaves me a little bit in the dark here.

The tank I want figure is 850lbs for a 90 gallon + a wooden stand (4FT Long)
1400 lbs for a 125 gallon + a wooden stand (6 FT Long)

The room, more specifically the wall that the tank and stand will be against, where it will be kept is directly on top of where the fireplace is on the lower floor. So in turn the chimney should be directly behind the wall.
If I go up into the attic I may be able to see which way the joist run and get a better picture of what to look for, but I’m no contractor. I don’t know what to look for.
This is a quick thing I drew up of the set-up of the 3 floors/rooms. Maybe this will help in determining if this is an supporting/load bearing wall.



Any help is greatly appreciated. I wouldn’t want this crashing through my floor into the living room. Better safe then sorry.
When I get home I will take a video of the attic and see which way the joist run up there if its any help.

Thanks again guys.

Maybe this video i made will help

http://youtu.be/kslP4zhd86E

125 gallons is huge and heavy.

Ask your insurance company if they will pay for damage caused by a leaking 125 gallon fishtank first. If they won't cover it, then don't get one. If you don't have renter's insurance, get it. Get it now.

Check your renter's contract. It may forbid fishtanks and/or waterbeds. If so, you may have a problem that way.

At 1400 lbs and four legs, your lb/ft^2 is going to be very high. If there is any structural issues, or even just a weak piece of plywood on the floor, then it can be a problem fast, resulting in the discussions with landlord and insurance companies, and their lawyers.

What about rocks and other fish amenities? They weigh more than water. What about all of the other stuff that may be placed on, in or under the tank? Filter, pump, food, lights, the weights all add up.

Just because the attic joists run in a specific direction, it won't tell you what sized joists are currently supporting the second floor. Based on current​ code, residential homes are designed for a 40 psf distributed live load. I can guarantee that either fish tank will likely exceed the current code values (not having all the tank dimensions prevents a quick calculation).

Does the existing fireplace go from floor to ceiling, or does it have a standard mantle? What kind of construction is the fireplace? Typically stone / masonry fireplaces will have an independent foundation to support their loads. If it goes floor to ceiling, you might be able to use it for additional load capacity; but no guarantees.

I do not recommend attempting to put this tank on the second floor without true structural investigation and analysis run on your home / rental by a local engineer. We do not have enough information to attempt an analysis through this forum.

I have an 180 gallon tank on my 1st floor above an open basement. Between water, tank, stand, filtration system, rocks, etc, it weighs well over 1 ton. Granted, I know it's sitting across 6 floor joists within a foot of a major steel beam, so there isn't a problem with mine.

Most stands (especially for tanks bigger than 50 gallons) are designed to equally distribute the load across the width along the floor. They typically do NOT have 4 legs (like a table), and are more like a water bed in that you have several long members in direct contact with the floor (tank stand builders are very aware of building codes - assuming you bought a commercially built stand).

You are correct in trying to determine the orientation of the floor joists, and it is very important to orient the tank so that it crosses as many as possible (in your case, 4-5 joists depending on size purchased). Also, it is very advantageous to put it as close to a load bearing wall as possible. This will reduce the amount of cantilevered weight and transfer more of the weight directly to the wall instead of through the floor joists.

I've never tried it on a floor, but depending on what flooring you have you may be able to use an electric stud finder to locate your joists. Your attic joists are oriented to complement your roof layout and may not reflect the floor layout, so I would avoid using that as a guide.

quick answer to finding joist orientation would be to poke a hole in the ceiling below and take a look.

Can you take a decent stud finder on the ceiling below and try and find which way the ceiling joists go?

I would have a hard time thinking that most semi modern houses couldn't support the weight of a waterbed, but maybe I'm wrong..

I dated a girl when I was in my 20s and she had a pretty large fish tank in her mobile home. Yes, mobile home. I remember the floor started sinking below the tank! But 1.) It was a mobile home and 2.) I remember her tank base had 4 legs which, of course, resulted in 4 concentrated points. Make sure you have a flat bottom on your tank base to distribute the load more evenly. You might consider putting it on the first floor, if possible. Good luck.