# Styrofoam Under Tank



## vstar (Dec 29, 2009)

I am in the process of building a stand for a 75 gal tank and would like to know if anybody ever put styrofoam underneath it and how thick is the styrofoam? I have seen it mentioned before.


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## trigger (Sep 6, 2002)

It really depends on the stand you are building. If it's a frame like outline where just the tank sides rest on, styrofoam is useless and maybe even bad. If you make a stand with a flat surface, styrofoam can help you to even the surface, so no stress point are on the bottom glass. I have three Juwel tanks which have their own plastic frame to lift the tank a little. You are actually voiding waranty if you'd put styrofoam underneath that. My corner tanks rest flat on a surface and I have a 2cm styrofoam board under that. I think basically, you don't want to have the whole bottom surface touch a hard surface.


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## Pali (Dec 22, 2009)

I have never seen a 75 g tank with plastic frame, but not saying it's not out there or common other places.

I got a few smaller tanks that came with plastic bottom frames, but removeable and I don't use them as they look like s**t. 
I just use styrofoam sheets, wraped in black cotton fabric also around 3/4" / 2 cm if they are placed on a flat surface. I have yet to need to change the fabric, oldest sheet have lasted me 6 years and still looks fine.

Is the tank alu framed or regula glass?

Unless it's framed I would build a stand with surface support and use styrofoam


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## prov356 (Sep 20, 2006)

I use it if building a rough 2X4 frame to cushion any imperfections, but as Trigger said, it depends on the frame and how you're building it. Best scenario is to make a stand that doesn't require styrofoam by making the surface it sits on flat.

One caution if using styrofoam. I used some 3/4" that I had lying around, and under some tanks it depressed a bit more on one side than the other. So, went to the trouble of making the racks level, but the styrofoam took it out of level. Ticked me off, but I'm not draining everything to remove it now. So, lesson learned is used something thin if you need to use something. I'd recommend the thin foam that comes in rolls at the building supply stores. It's about 4" wide and maybe an 1/8" of an inch thick. Typically is blue or pink.

Also keep the warranty in mind. Some manufacturers will void the warranty if you use it, some will void it if you don't, go figure. :-?

Just wanted to add that many will void the warranty if you build your own stand, so the styrofoam question becomes moot.


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## Benaiah (Aug 18, 2009)

Yes, I think it depends on the type of tank you have. I have a Glasscages aquarium, and that warranty requires that you put styrofoam between the tank and the stand. The bottom of the tank doesn't have a deep plastic rim - so a lot of the glass will rest on the surface. Since that's the case, having styro to smooth out any imperfections is good.


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## Toby_H (Apr 15, 2005)

If the tank to stand interface is not perfectly flat... then styrofoam can be a very good idea...

otherwise it's not at all necessary. Some manufacturers (such as glass cages) recommend it and others (such as all-glass) suggest against it...


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## Rhinox (Sep 10, 2009)

Sorry if I'm hihacking 

I just built a stand for my 125g tank and as it turns out, the top of the stand is slightly bowed upwards so that the middle of the stand is ~1/8" higher than the ends. The tank is glass, 125g. Don't know the brand. I've been told perfecto, but I don't know for sure. It does have a plastic frame on the bottom. I also purchased from craigslist, so I doubt I could claim any warrenty even if one exists.

I got a ~1"+ think layer of pink foam I'm planning on using under the stand (actually, a double layer of 1/2" nominal pink foam) that I will "uphoalster" with some black fabric I picked up. Currently, the foam covers the enter top of the stand, less cutouts for my corner overflows. Alternatively, I could just leave enough foam around the perimeter of the stand so that only the edges can touch the foam and the middle is clear down to the wooden top of the stand.

So, what do you think in this specific case? Foam or no foam? Thicker, thinner? Middle cut out or doesn't matter?


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## PfunMo (Jul 30, 2009)

To me the issue is having all points on the bottom of the tank supporting the weight as nearly evenly as practical. Working around foamboard over the years I have seen lots of places where it has compressed where thereis heavy pressure and less where the pressure is lower. That seems to me to be what is needed. I don't feel there is any advantage in using anything thicker than what the larger bump on the stand would be. A bump or bulge larger than 1/2" would make the stand defective by my standards and I would replace the stand rather than put more than 1/2" of pad under the tank. I don't have any tanks where the bottom is actually laying on the stand so I only use strips of foam around the edges where the weight is supported. I don't wrap mine in fabric but use latex flat black paint to conceal the edges. Oil base paint may eat the foam.


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## prov356 (Sep 20, 2006)

PhunMo said:


> I don't feel there is any advantage in using anything thicker than what the larger bump on the stand would be.


 :thumb: Agreed. I went thicker and it just caused me problems. I didn't even consider that irregularities in the foam might cause some areas to compress more than other areas. Depends on the type of foam, I guess. I used the typical white styrofoam that's used as insulation between wall studs.



Rhinox said:


> Alternatively, I could just leave enough foam around the perimeter of the stand so that only the edges can touch the foam and the middle is clear down to the wooden top of the stand.


That's what you want to do. One warning I received from Central Aquatics is to make sure that the foam does NOT press up against the bottom of the glass. Just place it under the edges. For a six footer, they suggested supporting corners and middle of long side. Nothing else was really necessary, but I don't see the harm in laying it all along the edges.


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## PfunMo (Jul 30, 2009)

I had forgotten about the white insulation board. I feel it is not worth the slight amount of difference in price. When I buy foam board, I'm usually using it first for insulation so the r-value makes the blue or pink well worth the added expense. Then when I'm using scraps for all kinds of other projects, I find the denser blue/pink to be so much more pleasant to work around. The little white balls are always somewhere I did not want them. Like inside my glasses. :x For anything where rubbing and appearance may matter, the blue is much more durable and has a finer grain. I find cutting it with a power saw makes a real mess but provides a really smooth edge that will take paint pretty nice.


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## 24Tropheus (Jun 21, 2006)

vstar said:


> I am in the process of building a stand for a 75 gal tank and would like to know if anybody ever put styrofoam underneath it and how thick is the styrofoam? I have seen it mentioned before.


Yes because some of the cheaper makes of tank here in the UK the guarantee is invalid unless you do this.
As the guys say go for as thin a strip as you can (or they say) as a well made tank with a well made stand just does not need this and thicker blocks can kind of compress and exagerate any lean the tank develops. A thin bottomed tank prob cracks or leaks for other reasons but if it invalidates your guarantee then you can be kind of on a loser (getting your money back) if you have not followed the tank makers instructions. :wink:


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## Toby_H (Apr 15, 2005)

PfunMo said:


> I don't feel there is any advantage in using anything thicker than what the larger bump on the stand would be. A bump or bulge larger than 1/2" would make the stand defective by my standards...


^^ That's some good stuff right there...


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## vstar (Dec 29, 2009)

Thanks for all the info. I just set-up a 29 gal. about a month ago. The stand I had was a cabinet that was built for a bathroom. The countertop on it had a slight concave in the center,so instead of putting shims in the center I bought a 1" thick styrofoam. But after putting the foam down and putting the tank on it,it still had a concave on the tank. So I put a shim in between the counter top and foam,now the tank set level and it put the foam up against the tank in the center. The foam did compress when I fill it up all around and hopefully will stay that way without compressing more. My thought was to build my stand out of 2x4 and build the top frame out of 2x6. But I think I will put a solid surface on due to the weight of a 75 gal. tank plus the weight of sand and water would really compress the styrofoam.


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## PfunMo (Jul 30, 2009)

The reason I use styro is because it is hard to get 2X lumber that has a full four feet without some small ridges or bulges. Sometimes it is only where the planing equipment has chattered as the board passed. I just feel more comfortable with a 1/2 inch of foam. The blue foam is quite uniform thoughout and as pressure is put on one spot that will sink down. This will only sink until the weight is fully settled. The higher spots have more pressure on them and will settle more. I feel this gives me a very uniform pressure all around. With bluefoam under a 75, I have about 1/16 inch of compression when using 1/2 inch foam for about a year. I would not do a full surface if my tank only rests on the perimeter as the center should never have anything touching it.


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## Rhinox (Sep 10, 2009)

ok, now you guys have me nervous... where was this information when I first asked how much foam I should use and got no answers 

Does anyone have any good information on how much foam compresses? I know its dependent on the density and type of foam, but there's got to be some info out there right? I mean, this pink and blue stuff is used under concrete pads sometimes, so its gotta be rated to handle the compression right?



> With bluefoam under a 75, I have about 1/16 inch of compression when using 1/2 inch foam for about a year. I would not do a full surface if my tank only rests on the perimeter as the center should never have anything touching it.


If its only compressing 1/16", it shouldn't matter whats in the middle because thats not going to be far enough for the glass to hit the foam anyways, right?

If you think about a 72" 125g tank with a 3/4" thick frame, thats 135 in^2 of area supporting the tank. Assuming the tank will weight no more than 1500-2000lbs fully loaded with sand and rock, thats still less than 15psi on the foam. How much compression does it take to hit the bottom pane of glass, and is 15psi enough to do it?


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## prov356 (Sep 20, 2006)

Most foam compresses little because of the low psi, so usually nothing to worry about. Plus as most tank bottoms are tempered glass, I find myself doubting the advice given me from the tank manufacturer anyway.

I once placed a 180 on some foam that I could easly compress between two fingers. I filled it waiting for it to get squashed under the weight. It didn't compress at all that I could see. I learned a lot about weight distribution that day.


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## PfunMo (Jul 30, 2009)

I have no worries about it hitting the glass bottom. Would not think it would hurt even if it did. For how much it compresses, I find you can stand on the blue or pink and it will only make a small indentation. When you think of a person on one foot it may be more PSI than a tank on it's base??? I guess the bottom line for me is that it just doesn't compress enough to notice and certainly not enough to worry. Stands, carpeting, padding and floors are of less uniform density so they are more prone to uneven settling than the foam to me.


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## 12 Volt Man (Sep 22, 2008)

when I was setting up my Aqueon (aka All-glass) 150g I looked into the styro debate.

I have never used stryo in 20 years of fishkeeping, but I had never set up a tank this big either.

my tank sits on a tube steel stand and I chose to follow their recommendation of NOT using stryofoam under their tanks. it has a "floating bottom" design in that the bottom glass never touches the stand. it "floats" on a one peice double braced plastic frame on the bottom.

Glasscages recommend styro for their tanks because there tanks are NOT a floating bottom design, the glass itself makes direct contact with the stand so that is why they recommend the use of foam for their tanks.

I would consider which style of tank you have (either floating bottom or regular flat bottom glass) and decide from there.


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## vstar (Dec 29, 2009)

I just measured my 1" white styrofoam under my 29 gal and it measured 7/8". I went to Menards today and seen the pink foam which is a lot denser. I also found some stuff they carry which look like a 5/8" thick 16"x16" rubber paver stone which I feel would really work good because of it density and it still give by squezzing it. I know that it would be able to handle heavy and big tank on it. I will go with it, if I need to. I would rather shims between the top (tank stand) and the rubber paver then shims between the top (tank stand) and the tank.


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## BillD (May 17, 2005)

A few things to consider. A tank should never be shimmed; only the stand should be shimmed. Floating bottom means that the bottom piece is inside the tank rather than under it. This supposedly allows it to absorb torsional forces better. Of course, this only works well with tanks that have bottom frames to protect the edges of the vertical panes.
I have yet to see a metal stand that was perfectly flat along the top. if it has a crown, the steel will flex under the weight of the tank. If it is bowed down all the weight is carried on the ends, and the tank supports all the weight. It is better in my view to have the weight evenly distributed.


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## 12 Volt Man (Sep 22, 2008)

"I have yet to see a metal stand that was perfectly flat along the top"

in 20 years of keeping fish with the steel stands available here in Ontario from Big Als, neither have I.. 

I am told that steel tubing is almost impossible to get exactly straight.

every steel stand I have ever had has had a slight gap in the middle, usually only visible if you shine a flashlight through. but they had the gap even before the tank was filled.

problem is, putting foam on such a stand does not do anything in such a situation.

when filled, the foam on the ends where its perfectly straight will be fully compressed and supported.

where the slight downward bow is, it will not be fully compressed and not fully supported.

visually, you might not see the gap anymore. but the tank is in no differerent of situation then before the styro was there. now, there will be a slight gap between the stryo and the stand rather than the tank and the stand. so we are back to square one.

I asked a tank manufacturer about gaps like this and they told me it does not matter as long as the ends are well supported, as glass tanks technically only need corner support. but Acrylic tanks need FULL support.

in fact, there is a thread on this board where someone asked Central Pet (the owners of Aqueon/Oceanic) and I believe they stated the same thing.

I know its counter intuitive to what we all might think, but thats what they tell us.

there is also a thread I believe on this board (you can tell I did some research on all this when I was setting up my 150g LOL) where someone explained the physics behind why glass tanks technically only need the ends well supported.

If I recall, it was because the bottom glass acts like a "girder" and becomes very difficult to break..

that being said, we all have to be comfortable with our setups.

if not having foam will keep you up at night wondering if your tank will break, then put foam.

In my case, I felt better following what the manufacturer stated for their tanks, so I went that route. so far so good <runs> LOL

I think that it is worth stating that most stands availabe from manufacturerers are not perfectly flat either. there are gaps too. I have seen many like this from both Perfecto and Aqueon (the Pine stands that are commonly available). so its not just with the metal tube stands.


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## BillD (May 17, 2005)

i have some metal stands I built with tubing, of a heavier wall thickness than commercial stands and even though I took great care selecting the pieces I used I still had rails that bowed down. The tanks I placed on 2 of these stands (4 tanks total) were rimless, so styro was a necessity. The styro on the ends compressed until the weight was distributed evenly. 
Tanks are in effect an open box beam so are structurally very strong. The weakness is the silicone holding them together. So, a tank with a floating bottom relies on the silicone to hold the sides in and all the weight of everything in the tank. A tank built with the sides on bottom, relies on the silicone to hold the sides in and not carry the weight of the tanks contents. The floating bottom is a trade off of a weaker build that is better able to deal with torsional forces. Since the manufacturer can't guarantee that the purchaser will set it up properly to avoid torsional forces, they go with the suspended bottom. It is also easier to assemble a tank with suspended bottom, as the sides go into the frame and the bottom is dropped in before the top rim goes on.
As far as acrylic tanks needing support across the bottom, ( because the bottom will sag) supporting a glass bottom will offer the same benefits. A bottom pane that is sitting on styro is much harder to break than one suspended.


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