Aquarium weight distribution

[Greg1218]

Hello everyone,

I'm looking for some recommendations to distribute an aquarium load.

Aquarium is 90gallons and 4' long by 20" wide. We can assume with stand + equipment it will be 1200lbs spread over 14 levelling feet
It will be placed in my apartment (second floor, timber building, #2 spf joists) across 3 perpendicular joists, up against a load bearing wall. (I'm assuming wall between neighbor apartment is load bearing)

I would like to place something underneath the aquarium to help distribute the load more evenly, and to possibly hit 5 joists total.
I was considering marine grade 1" plywood, but am unsure if the stiffness is enough.

Any recommendations for material, or issues with this load?

Thanks!

 

[dik]

How many 'legs', not 14? and are they just square tubes?

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[Greg1218]

The levelling feet are screw in, and maybe 1" diameter.

 

[dik]

How many 6 or 8 or more?

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[Greg1218]

There are 14 levelling feet.

 

[dhengr]

Greg1218:
Actually, a 4' long tank would involve 3 jst. spaces and 4 jsts.; and by moving it laterally one half jst. spa. it could start to involve/span 5 jsts. 14 leveling legs sounds kinda crazy, and extreme, but maybe so. You might put the legs (and tank) up on a podium made up of top & bot. plywd. skins and 3 - 2x4 stringers on edge, with some end 2x4's and cross blocking parallel to the fl. jsts. This would start to improve the load distribution down to the fl. jsts. You should check the fl. jsts. for bending, shear and bearing due to the added load. Check the wall and its top plate for strength. I would tie the tank and/or tank stand back to the wall, so it can’t tip forward.

 

[rb1957]

over 8 sq ft you're putting 900 lbs, or 4 "large" people.

the 4ft long tank looks to be well centered over 3 joists (16" centers, 3 joists = 2 spans = 32", so 8" overhand both ends.
So these joints will be seeing about 300 lbs each spread over 2'.

It not my area, but these numbers don't look frightening to me.
What running load are these joists designed for ?

"Hoffen wir mal, dass alles gut geht !"
General Paulus, Nov 1942, outside Stalingrad after the launch of Operation Uranus.

 

[Greg1218]

dhengr:
Good suggestion with the 2x4's, I think that would definitely distribute the load to the 2 outer joists. However, this means I would be raising the tank 4" off the ground, which is a little high. Do you think doubling up the 1" marine plywd (2" stacked) and no 2x4's would offer much load distribution benefit to the outer joists?

rb1957:
Yes I would agree with you that the numbers don't look frightening. There wouldn't be any catastrophic failure with this load.
The area of concern is the small amount of sag that may happen overtime. The worst thing for an aquarium to experience is a shifting or flexing of the stand the aquarium sits on.
If the stand starts to bow, it will put force on the silicone that holds the aquarium glass together, and this causes seams to blow. 90gallons of saltwater on the floor would be a nightmare in an apartment.

Joists are 11ft and are 2x10’s

Let me know what you think.
And thanks for the responses so far guys!

 

[XR250]

Dbl. 1" plywood would be pretty stiff if glued together. I imagine it would do what you needed it to do.

 

[Greg1218]

Xr250:

Thanks, I think that’s a great idea. 2” ply glued together should do it.

 

[kingnero]

I kind of disagree. Probably double plywood would be enough to counteract sag inbetween the joists, but it will also add significantly to the weight, and won't help against global sag or twist. I've put a large aquarium on a piece of styrofoam 40 mm thick (1" 1/2), and that is supported on a steel frame. The styrofoam will easily handle small to medium deformations, weighs next to nothing and can be hidden using wood trim front and sides.

 

[XR250]

I hardly think the 9 psf the plywood weighs is significant in the grand scheme of things. How does the steel frame work any better? What is its moment of inertia? I would think it would work better than a steel frame as far as twist goes.

 

[kingnero]

Perhaps I wasn't clear, My setup was a steel frame with no intermediate legs. To mitigate problems related due to deformation (it was a long beam with only supports at the end), the styrofoam was used.
The styrofoam is there to provide full bearing in case of any deformation.

So, for Greg1218, if he wants full bearing, I would prefer the styrofoam over 2x 1" plywood glued together.

 

[Rogue909]

I'd be more worried about the load of each leveling foot on the immediate ground than the combined load. 1" round foot = 109psi. Pending what the floor is made of that could leave an annoying mark on the floor once it sits for a bit. To counter it - lay down 2 pcs of 2x4 so it raises the height of the stand by the 2" side (1.5"). That would distribute the weight of the 1" round foot and give you the similar benefits of the 2" plywood without all the hassle.