What's Under Your Fish Tank? And, I Don't Mean Your Stand.

[JChristophersAdventures]

Something most of us probably don't give much thought to is what's really under our fish tank(s). I mean what's holding it all up... the floor... the building... the foundation. And, for some people, it might not be any big deal. Smaller tanks generally don't weight any more than most pieces of furniture and most floors/buildings/foundations are designed to hold all that and then some.

But, for larger tanks (I would start thinking about these things for sure at around 55 gallons and up), it could be a very important consideration for our investment in the fish hobby, not to mention our safety. Earlier today, I installed a floor jack under our house specifically targeting the space right below the piano holding my 75G project. You can read more specifically about it in my journal: Family Heirloom Gets New Life.

Old buildings, weak floors, living one or more stories above the ground level, and yes... even concrete can have potential issues.

Here's some weight and other fun information by tank size:

This can be a lot of weight in a relatively small area. In my case, the old piano weighs very close to what the 75G weighs full of water with a total combined weight of over 1400 lbs!

There are things you can do to mitigate potential problems.

If your tank is above ground floor level (1) you want to make sure it is against a load bearing wall (in most but not all cases, this is an outside wall which is designed to support the house and will easily accommodate the added weight... you might want to consider fastening the aquarium stand to that wall for even more security). Not all walls are structural. (2) Some stand designs spread the weight of the aquarium over a larger area than others, thereby reducing the impact in any specific spot on the floor. Racks built with 2x4s or similar construction are usually very effective at doing this. Stands with 4 small/narrow legs concentrate the all the weight to those 4 spots on the floor.

If you are on concrete, either a basement, or a slab foundation, you are less likely to have problems, however, not always. A neighbor, just down our street, recently went to her garage one morning, only to find that its concrete slab had developed massive cracks and sunk around 4" along both walls to the right/left of the bay doors.

The gutters had be come clogged and a the torrent of recent rain concentrated by the roof, had carried away a foot or so of the ground underneath the slab, washing away all the support. The result was a sudden collapse of large areas of the garage floor. What a mess. I can only imagine how big the mess would have been had that happened in somebody's fish room! Slab houses and full basements are also not immune to foundation shift and failures.

Its probably a good idea to inspect things at least a couple times a year and do some basic maintenance. Just say'n'. Thanks.

 

[Fish Folk]

Yep. Moved all but one tank to concrete-floor basement. 

[PineSong]

My house is only @60 years old and very sturdy, but I would send a brave soul into the crawlspace to put in supports if I was adding a big tank. I'm always kind of hmmmm when I see folks who live in rinky dink apartment buildings displaying multiple very large tanks in FB groups....would not want to live right under them.

[AndEEss]

My floor under my 143g tank is 5" wide hickory boards, with the planks themselves alternating and offset from each other so that they extend 3' on each side of the tank. Underneath, 2x8s at 16" spacing.

[JChristophersAdventures]

@PineSong Yes, many years ago for a short time, I lived in a 2nd floor apartment... let's just say I had some tanks... and leave it at that! lol

@AndEEss Sounds good to me... it is important to distribute the weight across as much area as practically possible like you have done. While I was scooting around down there lying on my back, I was shocked to find that while the old house was framed on huge timbers, an entire run of floor joist was cut and removed to make room for a large run of duct work... not smart on their part, but typical of the dumb things people did when adding central air, plumbing and electrical to old houses that were originally built before all that came along (and yes, this was done in the same room as the piano aquarium, but fortunately not right under it).

I was very glad I decided to put the floor jack under the tank area. Things even feel more solid walking around the area now. The jack only cost $25 (being only 1 1/2 foot long) that's some pretty cheap insurance. Thanks.

[Sora]

I was actually really worried about this when I got my 55 gallon, because I put it in my room on the second floor. My house is around 50 years old with wood floors.. I just went in my closet and checked which way my floor joists were going to make sure that the tank would be resting on more than one joist so it would have more support. no problems yet, lol 🤞

[JChristophersAdventures]

@Sora And, chances are you probably won't as long as the current situation remains as it is. I could do the math, but lets just suffice to say that an average sized adult  person walking, actually places more force (effective weight) against the floor as their foot comes down and their weight shifts completely to one foot, than a full 55G does sitting statically there in the room (assuming the stand does a reasonable job spreading the weight around). Multiply that by however many adults might be in the room at one time and remember that houses are designed for both furniture and people walking around at the same time.

Obviously a 55G weighs more than typical furniture, so I wouldn't be trying that with a large number of tanks and then having a dance party up there! lol

 

Edited September 6, 2023 by JChristophersAdventures

[Tombeaux]

I'll throw my situation into the conversation. I worry about this often.

I've looked into building codes and saw that most floors have a rating of 40ish pounds per square foot over the WHOLE area of the floor.... so if your space is 500sq ft in theory it should hold 20,000lbs of your stuff. But that still seems odd to me. There's usually a safety factor in those standards, let's say 2.5 or times so 100lbs or 120lbs per square foot. It's also got to be true that where there are tubs, fridges, water heaters then the floor is probably reinforced.

Now, my rimless 66 gallon is probably about 750lbs and the square footage of my tank stand is 5.43 (it's in cm, 100cm long by 50cm wide) which means approximately 138lbs per square foot of tank. Although I am over the psf, I know my second story apartment floor is concrete, and is probably reinforced. The stand has a solid piece of plywood bottom and it's in a corner with an outfacing wall. 

I still get worried, but it's been there going on two years. Does all my rambling check out? Do the building codes tell us anything? since that is what I am basing my math from..

[lefty o]

im on concrete that was poured in 1957. so far, so good.

[JChristophersAdventures]

@Tombeaux Keep in mind that the rating per square foot is subject to a lot of factors and is just as much a relative measure as anything, meaning that like mpg on a car it is designed for comparing to other vehicles rather than an indication of the mileage you will get.

So, with a car with an mpg of 50 we would expect to do twice as well as one that rates at 25... it doesn't mean you will get either of these mileages if your drove these cars. Likewise, we could expect a 80 lbs/square foot to be twice as strong as 40 lbs/square foot (given consistent measurement standards are used).

Like the car mpg, it is all relative. So, just because you appear to have exceeded the rating in certain spots of the floor in no way indicates that collapse will occur. 20,000 lbs would be the equivalent of 10 1 ton pickup trucks! Do I think the floor would support that? I don't know, but the point is that I suspect you'll be okay with the typical household set-up. Bathtubs, refrigerators, washers & dryers... these things all weigh a lot, but they are easily supported by a standard floor.

Having said that, I would think twice about building a 2nd story fish room! lol Thanks.

Edited September 7, 2023 by JChristophersAdventures