# Foam under tank



## joevc1 (Dec 17, 2007)

Can anyone suggest what type of foam is used under the tank.
I'm building a DIY stand for a 125g and need to plan for it.
Also, how thick is it and does it compress with the weight of the tank?
The trim around the top of the stand has to cover the foam and tank rim.

Thanks.


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## Mcdaphnia (Dec 16, 2003)

I cut pieces out of the flat parts of styrofoam egg cartons. It will squish with time, but not as drastically as thicker but less dense styro. Did I mention it's free?


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## joevc1 (Dec 17, 2007)

Well, stand is almost done and I'm going to use foamcore boards that are 3/16" thick.
I plan to use 2 layers, what would be the best option?

Option 1:

Tank
1 layer of foam
plywood top
1 layer of foam
2x4 frame

or

Option 2:

Tank
2 layers of foam
plywood top
2x4 frame

I like option 1 since the foam will fill in any gaps between the plywood and also the tank.

All comments welcome. Thanks.


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## Big Den (Apr 5, 2008)

I always use styrafoam 1 inch thick, same size as bottom of tank. If you are using 2 pieces its best with one on top of other. The object is that, if there are any small lumps and bumps the foam will compress over it. It also acts as a shock absorber. Also I would make the top at least 18mm plywood. What are the tank dimensions?


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## joevc1 (Dec 17, 2007)

Big Den said:


> I always use styrafoam 1 inch thick, same size as bottom of tank. If you are using 2 pieces its best with one on top of other. The object is that, if there are any small lumps and bumps the foam will compress over it. It also acts as a shock absorber. Also I would make the top at least 18mm plywood. What are the tank dimensions?


The tank is a 125g, 72"x18", with a 3/4" plywood base.
I was going to put 1 layer under the plywood to compensate for any "bumps" and 1 over it and then the tank.


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## Big Den (Apr 5, 2008)

No! put both layers under the tank. Under the plywood would serve no purpose.


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## Mcdaphnia (Dec 16, 2003)

Big Den said:


> No! put both layers under the tank. Under the plywood would serve no purpose.


 Well, a layer under the plywood would still act as insulation. You would not want the plywood supported by the foam since it would then be unstable.

As to using two layers of foam or any number of layers totalling one inch..... If your tank has a floating bottom, and nearly all do any more, you do not want the foam under the tank to be as thick or thicker than the space under the floating glass bottom. If the sides crush down into the foam which they will, a too thick foam sheet will be pushing up on the tank bottom, risking a leak or crack.


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## joevc1 (Dec 17, 2007)

First, the foam I have is only 3/16 of an inch thick, two layers would only be 3/8 of an inch.
I thought if I put a layer under the plywood it would fill in any uneven gaps between the stand frame and the plywood deck. I realize it would crush down a bit but it would also fill in any gaps.
Then the plywood would be more even/level throughout its span. The second layer on top of the plywood would also act as a cushion.

The frame is built with 2x4 vertical studs all cut to the same exact size, but the gluing and screwing assembly could have caused something to be slightly off. This was my thought behind putting the foam under the plywood. Or, I'll just put 2 layers on top and be done with it.

So, I'm back to my original question, option 1 or 2.


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## dergibog (May 30, 2005)

I see what you're saying joecv1. I think it makes sence too. But, if it were me, I think I'd just go with option 2. That should accomplish everything you're trying to do.
Keep us posted on your progress. I'm going to build a stand for my 180 and I plan on doing the same thing. Good luck. Post pics if you are able! opcorn:


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## illy-d (Nov 6, 2005)

Use a level and check the surface of the stand for high spots & low spots... If you have discrepancies greater than 3/8 you need to break out the belt sander!

Most glass aquariums come with a black or wood veneer plastic trim around the top & bottom of the tank. The bottom trim is thick enough that it keeps the glass a couple of mm above the surface of the stand anyhow...

I found this stuff at Home Depot that looks kind of like carpet underlay (but it's not) that I use. It's only a 1/4" thick at the most. (it was under my 135)


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## Mcdaphnia (Dec 16, 2003)

illy-d said:


> Use a level and check the surface of the stand for high spots & low spots... If you have discrepancies greater than 3/8 you need to break out the belt sander!
> 
> Most glass aquariums come with a black or wood veneer plastic trim around the top & bottom of the tank. The bottom trim is thick enough that it keeps the glass a couple of mm above the surface of the stand anyhow...
> 
> I found this stuff at Home Depot that looks kind of like carpet underlay (but it's not) that I use. It's only a 1/4" thick at the most. (it was under my 135)


Somehow that reminds me of a stand I built for a frameless tank in 1970. It was built using the specs for a pool table and had a green felt top for the tank to sit on.


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## joevc1 (Dec 17, 2007)

I went ahead and put a layer under the plywood just for peace of mind.










And here it is, so far.




























Sorry fot the tarp, rainning.


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## dergibog (May 30, 2005)

Well done my friend! :thumb:


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## Mcdaphnia (Dec 16, 2003)

joevc1 said:


> I went ahead and put a layer under the plywood just for peace of mind.
> 
> ....


That layer would do the opposite to my peace of mind. It would let the plywood warp and twist since it provides no solid support. If the plywood is screwed down through the foam, the screws could pop up into the tank bottom as the foam compresses.


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