Advice from Tank Builder please!

[Greggo12]

Hey everyone,

I just received a custom aquarium after having a RS 250 G2 seam start failing, and have some questions about the build of the tank I received.
I would appreciate if the comments were kept to tank builders or people very knowledge about builds and structural strength.

42" long, 19" wide, 20" tall.
12mm glass bottom, 10mm everywhere else.
Euro bracing TOP and BOTTOM.

The aquarium sits on OSB board, and then sits on a welded steel square tubing stand.

I did the livestock swap and noticed after that only the corners of the tank (one corner just barely) is contacting the stand.
There is a 0.030" gap between the board and the steel stand in the dead centre, front side and back side, that spans about 2 feet and tapers to smaller gaps until the corners.
That's about a credit card sized gap at the worst spot.

The tank is level.

The builder said the tank is overbuilt and this shouldn't be an issue and he isn't concerned, but I would like some other opinions.
Silicone used is Tremco Proglaze
Thank you so much!

 

[Randy Holmes-Farley Verified Community Expert]

I’ll move this to the main forum,, :)

 

[Greggo12]

I’ll move this to the main forum,, :)

Thanks Randy!

 

[Freenow54]

Thanks Randy!

Do a member search for Uncommonsense

 

[fishguy242]

You do not want OSB between the tank and stand, will absorb moisture and bump and buckle
maybe plywood ,did the mfg not recommend a pad ?
1/2 foamboard will work if need be

 

[UncommonSense]

As @fishguy242 pointed out, OSB is not a wise choice of material for the top plate of a stand! (I’m also curious if there are any metal braces running front to rear to prevent the center of the top plate from bowing?)



On to the air gap:

— OSB is also notoriously not perfectly flat, and this piece does seem to have a distinct bow… (plywood sheathing/cladding can also have this issue):

— do you happen to have a 2-4ft level, yardstick, or other fairly usable straight edge you could place against the bottom of that beam of steel framing in your video? This will allow you to determine if the air gap is due to bowed steel framing, or bowed OSB sheet!

 

[RedReefer]

Probably in the osb board. Use a rubber mat or foam board.

 

[Greggo12]

Thanks for the responses guys!

I put a 2x4 up against the bottom beam and it is definitely out by > 0.030” on one end. It seems the beam is bowed both front and back, probably from welding. Another tank builder said this gap is extremely common for steel tubing stands.

Yes there are 2 cross braces going front to back. Neither is touching the tank. From what I understand with rimless builds, perimeter contact (or even just 4 corners) is usually enough.

I agree that OSB is very amateurish for a tank builder. Unfortunately the board was siliconed to the bottom of the aquarium .

The tank arrived at night, and the swap over from a failing RS 250 G2 seam occurred the next morning. Not much time to figure things out.

Current plan:
1) use feeler gauges to measure deflection in every area of the perimeter including the 2 cross braces.
2) 3d print 6” long 100% infill PETG shims with varying thicknesses to fill these perimeter gaps.
3) remove half the water, shim everywhere between OSB and steel (will not force any shims in to avoid pressure points)
4) Fill back up with water.

Think this sounds reasonable?

 

[UncommonSense]

I’d double check using something a bit more reliably straight than a 2x4! — wood has a bad habit of warping and bending substantially!

 

[Greggo12]

Checked with one of the side panels that appears very straight, got the same gap. The droop in steel is also apparent when you simply look down the beam.

 

[UncommonSense]

… what do you think of getting a temporary holding tank, like a plastic stock tank, and returning this questionably supported aquarium?

 

[UncommonSense]

I agree that OSB is very amateurish for a tank builder. Unfortunately the board was siliconed to the bottom of the aquarium

Also, is this OSB board siliconed to the tank bottom just by the small quantity of silicone which gets squished out of the bottom seams during tank assembly? Or is it very intentionally and liberally siliconed down across the whole tank bottom?

(My thought being that you may be able to cut the OSB free of the tank and use a proper stand top plate which will be easier to shim, and won’t swell irregularly when wetted!)

 

[Greggo12]

I think I would expect substantial livestock die off if I had to put everything in a holding tank while i wait for a new stand/tank. There’s also a reasonable chance the builder wouldn’t make another stand given hes comfortable with how the setup currently is.
While I do value the flooring & people living below me more than the tank itself, if there’s a reasonable way to ensure the tank is well supported by not removing the inhabitants I would prefer that option.

There are deliberate silicone lines between the board and tank on the ends of the aquarium, so I think removing it from the bottom of the tank could be challenging.

 

[UncommonSense]

I think I would expect substantial livestock die off if I had to put everything in a holding tank while i wait for a new stand/tank. There’s also a reasonable chance the builder wouldn’t make another stand given hes comfortable with how the setup currently is.
While I do value the flooring & people living below me more than the tank itself, if there’s a reasonable way to ensure the tank is well supported by not removing the inhabitants I would prefer that option.

There are deliberate silicone lines between the board and tank on the ends of the aquarium, so I think removing it from the bottom of the tank could be challenging.

Hmm.., in this case, I suppose the printed shims from high compressive strength plastic will likely be your best-bet… that, or printing a custom monolithic shim for each side that follows the bow in the steel from end to end, and leaves you with a plane frame top to set the OSB clad tank on…