# Is Cushion Under a Tank Really Mandatory?



## defiesexistence (Sep 13, 2010)

Or at least advised? I'm sure you could be fine with a small tank, but does it really make a significant difference of pressure on the bottom glass of a larger tank?


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## mcubed45 (Jun 30, 2010)

are you talkin about a glass or an acrylic tank? with glass tanks, the actual glass doesn't touch the the surface. it's supported by the rim. load distribution isn't much of a problem unless you've got a very uneven surface.

acrylic tanks require the entire bottom pane to be supported. with acrylics, some sort of cushion helps to ensure equal load distribution.


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## Captivate05 (Feb 23, 2010)

Uneven pressure seems to be what takes out larger tanks after a while. While it may not be a big deal, once you get up to 100+ gallons that's A LOT of weight to trust to glass, silicone, and plastic. IMO, that cushion is worth while for larger tanks as a precaution. I'd rather just get the cushion first off then regret not getting it if the bottom of the tank should split a seam.


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## ridethespiral (Aug 5, 2010)

If your tank has a trim on the bottom, and your stand is not too unlevel or warped you will be fine. My 75g has nothing between it and the 2x4s of the stand 

If you have an all glass rimless tank, definatly use some foam or something


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## defiesexistence (Sep 13, 2010)

It's a 55g glass. Stand's not the best, but not the worst. Particle board, pffh.

What about a sheet of polystyrene, just to be safe?


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## majstor76 (Jun 11, 2010)

defiesexistence said:


> It's a 55g glass. Stand's not the best, but not the worst. Particle board, pffh.
> 
> What about a sheet of polystyrene, just to be safe?


Every tank should have cushion under, IMHO. Aquariums are years and years on same stands and wood warps (some more, some less) due to water, pressure and moisture. 1/2 m2 of foam for your 55g cost next to nothing so why calculate at all. Take 1/2 inch thickness


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## defiesexistence (Sep 13, 2010)

Thanks Majstor, I agree with the cushion thing now.

But what do do you all think of some 3/8 inch polystyrene?


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## majstor76 (Jun 11, 2010)

defiesexistence said:


> Thanks Majstor, I agree with the cushion thing now.
> 
> But what do do you all think of some 3/8 inch polystyrene?


3/8 inch is about 9 mm , yes? Well i have 10 mm cushion under 110g so 9 mm will be ok. 
And particle board is better option for stand than wood because it warps less


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## defiesexistence (Sep 13, 2010)

Thanks! Prompt replies too. I was also wondering, the sheet is a little too tall (maybe 2 mm) for under the tank. Should it still be fine? (It will be compressed, after all, but would this counteract the initial pressure from the water with any ill effects?)


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## majstor76 (Jun 11, 2010)

I dont understand how can sheet be 2 mm too tall? Too tall for what?


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## defiesexistence (Sep 13, 2010)

The difference in height between the rim and the bottom glass. There's a hollow (of sorts) under the tank, caused by the rim, making space between the bottom glass and the stand. This is where I was planning on putting the polystyrene, but it's a couple mm tall for the hollow. Hope that made sense?

First questions still stand, and thanks again.


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## majstor76 (Jun 11, 2010)

Aha, i understand. I have also one smallish aquarium with metal rim (from the 70s, silicone was not what is today so they reinforced it that way) and have gap of few mm under it due to thicker metal rim.
I was asking myself too how to handle the cushioning so i cut and put foam to fit bottom glass without rim, put some water into tank to let it sit on foam and then pushed strips of foam under metal rim (all around)


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## SNAKEMANVET (Jan 6, 2011)

If tank has plastic trim on bottom you shouldn't need anything under tank.If you place styrofoam that is too thick it can bust the bottom glass.I would put foam under a tank with no trim.Both of my tanks 120 and 240 have a 1/2'' foam under them,they have no trim that way it helps if any part of the solid surface is not perfectly even.htp


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## Wasserpest (Jun 12, 2003)

defiesexistence said:


> The difference in height between the rim and the bottom glass. There's a hollow (of sorts) under the tank, caused by the rim, making space between the bottom glass and the stand. This is where I was planning on putting the polystyrene, but it's a couple mm tall for the hollow. Hope that made sense?
> 
> First questions still stand, and thanks again.





SNAKEMANVET said:


> If tank has plastic trim on bottom you shouldn't need anything under tank.If you place styrofoam that is too thick it can bust the bottom glass.I would put foam under a tank with no trim.Both of my tanks 120 and 240 have a 1/2'' foam under them,they have no trim that way it helps if any part of the solid surface is not perfectly even.htp


Agreed! Don't place a styrofoam sheet just under the glass inside the rim. If want to use it, make sure the rim rests on the same styrofoam sheet as well.


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## defiesexistence (Sep 13, 2010)

Wow, thanks to the three of you!

Pink polystyrene is pretty unsightly....

So if I have a level surface, I don't particularly need to bother with a support?


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## OverStocked (May 26, 2007)

defiesexistence said:


> The difference in height between the rim and the bottom glass. There's a hollow (of sorts) under the tank, caused by the rim, making space between the bottom glass and the stand. This is where I was planning on putting the polystyrene, but it's a couple mm tall for the hollow. Hope that made sense?
> 
> First questions still stand, and thanks again.


Do NOT fill the cap and place pressure on the bottom pane of glass. It is not designed to rest on the bottom glass. It is designed to rest on the rim.


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## majstor76 (Jun 11, 2010)

over_stocked said:


> Do NOT fill the cap and place pressure on the bottom pane of glass. It is not designed to rest on the bottom glass. It is designed to rest on the rim.


Every aquarium is designed to lay on its surface. It can be with or without cushion and i didnt tell him to put foam just under middle


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## OverStocked (May 26, 2007)

majstor76 said:


> Every aquarium is designed to lay on its surface. It can be with or without cushion and i didnt tell him to put foam just under middle


did you notice that I did not quote you and I quoted the OP? I was replying to his post....

Rimmed aquariums have tempered, thinner bottoms than rimless aquariums. They are DESIGNED to sit on the RIM. PUSHING on that glass can easily lead to failure. The weight is meant to be carried by the rim. If you were rimless, it would be carried evenly across the bottom, but when there is a rim you can not evenly support the rim and the bottom glass. This will cause deflection and likely failure.


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## defiesexistence (Sep 13, 2010)

Her, actually, but I don't mind :icon_mrgr

Thanks for saying why, Justin. I was wondering the reasoning behind the posts. So everyone's in agreement as far as not putting foam in the middle, without it being on the rim. It's settled, then, and I'll fill as is, so long as it's level?


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## majstor76 (Jun 11, 2010)

defiesexistence said:


> Her, actually, but I don't mind :icon_mrgr


Gomenasai, you have "sex" in your nick so i assumed you are male


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## defiesexistence (Sep 13, 2010)

...Ah-kay. Majstor-san, like I said, I don't mind. And I wasn't planning on my nickname being perceived like that, with defy being plural, but anyhow, I should probably ask a mod to help me change it.

Soooo, time get a level and get to work. Thanks for your help, everyone!


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## Captivate05 (Feb 23, 2010)

You know, for a 55g I probably wouldn't worry too much. It's a lot of weight, but by "large" I was more or less referring to 100g+. The only tanks I've heard of splitting seams were 125g and up. Probably is still a good idea to put some cheap foam down underneath it, but I wouldn't stress out about it.

I agree with Overstocked: make sure the foam goes under the rim, not under the glass. You'll defeat the whole point if you let the glass rest on something. Suddenly that cheap piece of foam you got for insurance on your tank could very well be what undoes it.


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## defiesexistence (Sep 13, 2010)

Oaky-dokay, everyone is in agreement. Thanks for the replies!


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## Tamelesstgr (Jan 11, 2008)

Well, my 55 gallon was on a stand with 3/4" solid oak top, and all though it was used, mine sprank a leak. Had I had additional support under it who knows. I will be placing something under my next large tank, wife was not happy and it ended my aquarium hobby for awhile.


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## x2h (Dec 23, 2008)

my tank stand top is empty, the tank is sitting on its rims, how can i put cushion under the tank if there nothing to support the cushion...


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## Cuchulainn (Nov 2, 2010)

x2h said:


> my tank stand top is empty, the tank is sitting on its rims, how can i put cushion under the tank if there nothing to support the cushion...


You don't need to.


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## talontsiawd (Oct 19, 2008)

As said, just to reiterate, don't put anything that the actual glass rests on for a rimmed tank. It may push the glass upwards over time.

I don't think it is necessary by any means but I always put the stuff you put in kitchen drawers. It is a checkered pattern foam that is about 2-3mm thick. I don't do it for safety as much as it gives some room for water to evaporate when inevitably spilled on the stand, plus the tank doesn't stick to the stand over many years, making it easier to move, tear down to clean, etc. It comes in black which makes it very hard to see.


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## accordztech (Dec 6, 2004)

talontsiawd said:


> As said, just to reiterate, don't put anything that the actual glass rests on for a rimmed tank. It may push the glass upwards over time.


What about rocks that are sitting on the glass inside, wont it do the same thing?


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## talontsiawd (Oct 19, 2008)

accordztech said:


> What about rocks that are sitting on the glass inside, wont it do the same thing?


No, on a rimmed tank, rocks would be pushing towards the rim (support).


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