# Putting styrofoam under the tank before setup



## jldean78 (Aug 6, 2008)

Hello,

I was wondering what the pro's and con's are for putting styrofoam under the tank before setup. Anyone have feedback on this?

Thx


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## Dave27 (Dec 22, 2008)

I recommend that you don't do it. The styrofoam will deform (compress) where the tank frame hits it, and transfer load to the bottom of the tank if the styrofoam is a large piece that fits the bottom of the tank. This is usually glass, although some really old tanks had slate. The tank was designed to carry its weight plus weight of water on the frame, not on the bottom glass. It might not break right away, but you will be loading the system in a way that was not intended by the designers. Water weighs 62.4 pounds per cubic foot, about 7.5 pounds per gallon so you can see there are some big forces. If you only put the styrofoam around the edges, you will be watching the system deform as you fill it and if one region deforms more than the others, it could become unstable, tilt, and then the water will move to the end that is deforming and it will deform faster.

Also, the styrofoam is typically porous....thus, when the inevitable water spill comes, it will take longer to dry out.

The base for the tank (the stand, if you will) needs to be very stiff and off sufficient strength so that the tank does not need to support any shear loads that would occur if the base flexed or deformed. It also has to be flat so that the tank sits on it without any rocking. If not, when the water goes in, the tank will deform and introduce shearing stresses to the glass and seals/joints

I put some 10 gal tanks on a marble table once and used 5 pieces of 2X2 wood to support the frame. The wood was cut from a single piece so the dimensions were identical and the supports ran the short way. I also once mounted a 30 gallon tank on 3/4" vinyl covered particle board that sat on top of a table. These were schemes to protect the table.

Hoped this helped.


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## TheLaxPlayer (Dec 21, 2003)

My understanding is that you'd use a thin sheet of foam, 1/4" or less which is only thick enough to ensure that the load is spread around on the frame evenly, not thick enough that it would ever come in contact with the glass. That said, I've never tried it and I'm interested in the outcome of this thread as well.


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## boredatwork (Sep 14, 2007)

TheLaxPlayer said:


> I'm interested in the outcome of this thread as well.


I wouldn't get your hopes up. First of all this is a commonly posted topic. If you do a search you will find many posts dedicated to this, and I think you will interesting if not useful discussions.

Secondly, in general you will get two types of response:

1. Yes you should do it
2. No you shouldn't do it

They will be accompanied by some "explanations" but ultimately never very helpful at least in terms of actually making a decision.

In my opinion the best thing to do is ask the manufacturer of your tank what they recommend. I know there are some manufacturers that do recommend its use, and will will specify the thickness etc. And there are some that will tell you that if you use it, it will void the warranty. So I definitely think contacting the manufacturer is the safest and most logical thing to do.


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## Number6 (Mar 13, 2003)

jldean78 said:


> Hello,
> 
> I was wondering what the pro's and con's are for putting styrofoam under the tank before setup. Anyone have feedback on this?
> 
> Thx


 Pro, you even out any tiny deformity or burs in the stand avoiding some bizarre stress point on the tank.

Cons, none that I am aware of.

Dave27, not sure what styro you're thinking of... but nobody should be using that stuff... the regular thin kind from home depot is what you use... :thumb:


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## blueinfinity (Jul 17, 2003)

wait no one seemed to ask..

are we talking a rimmed tank or a flat bottom tank? the black trim tanks i would say no. the flat bottom i am 110% to the yes. because as number6 said. even the smallest uneven spot can weaken the tank.

1/4" or less


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## boredatwork (Sep 14, 2007)

Number6 said:


> jldean78 said:
> 
> 
> > Hello,
> ...


There certainly are cons. Even though it can compress, styrofam is not magic. It will still produce a force on the tank. Through the same argument used to justify using it, you can use it against. In other words, if styrofoam can produce enough support to even out an uneven sport on the stand, at the same time, any uneven spots in the stand can be exaggerated by using foam.

In all honesty, if either scenario is true the argument should not be whether or not to use the stryfoam, but why are you using that stand?


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## Number6 (Mar 13, 2003)

I'm not going to try and claim expertise on how foam compresses, but I've had engineers, construction folks, handymen come see large tank setups and even had a chance to visit a company who creates foam of all kinds from the chemicals...

without exception, they all said that styrofoam was a good idea. The resounding reason was the way that styrofoam compresses... They all said that no, the styro will not create stress on the tank... they all seemed mildy amused at how clueless I was to even ask that. They all agreed that any burr or other minor defect of the wood would cut up into the foam and provided that the defect was shorter than the depth of the stryo, it would avoid the stress point.

It's also interesting that some manufacturers demand it... 
http://www.glasscages.com/?sAction=AqWarranty

So... do I claim to be an expert? Nope... don't care. I know that in 20 years of use on black trimmed, flat glass bottomed, bare glass sided, and probably tank styles I've forgotten about, I've yet to have any tank break with styro under it...

and I've never *not *put styrofoam under a tank.

So what Con is there? I'm game... I'll do a search to see if you've already answered this, but either way, you've got quite a ways to convince me that none of the engineers at the foam plant knew what they were talking about. You might do it, but it's a challenge


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## BillD (May 17, 2005)

I don't know of any styro that will compress enough with the weight of the tank that it will touch the raised bottom of a framed tank. As an example, I have a 35 that sits on 3/4" styro on an open metal stand. The tank when full, barely indents the styro. The long cross member on the stand, which I built myself, is not perfectly straight even though I went to great lengths to use the starightest material posible. It is 1 1/4" square tube, with 1/8" wall thickness, that is double the wall thickness of the commercial stand I have seen. The styro compresses only enough to equalize the pressure on the bottom of the frame. I have 2 other steel stands that hold 2 frameless tanks each. The styro compressed on the ends where necessary to support the entire outside edge of the tanks. So, as the "manufacturer" of said tanks, I will state that the styro is essential. I have to agree completely with Number 6 on this.


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## Number6 (Mar 13, 2003)

thanks Bill... and just in case anyone is wondering what styrofoam we are all talking about, it's the consrtuction panels in Home depot and comes in rigid pink or blue. There are white sheets of the cheaper stuff, and though some folks don't like that stuff, I've used all three without a single one of these types compressing so much that it ever touches the tank bottom on a floating bottom tank. Heck, even after years, the compression was surprisingly little even under very large tanks.

As a cautionary tale, as I went and read an article on the topic, I am not, nor ever would suggest using strofoam to level a tank on a stand or even to level a stand... the suggestions I have always read about and talked about with fellow hobbyists is that styrofoam on a perfectly sturdy and stable stand designed for aquariums provided insurance against burrs or similar defects.

Hope that helps.


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## boredatwork (Sep 14, 2007)

I can't say I am expert either. Far from it. I am trying to say from an argument point of view, it has to go both ways.

The point is this. If you can make an argument that styrofoam is beneficial, which I am not disagreeing with, then you can use that same argument to say that it can have adverse effects.

If the you argue that the styrofoam is beneficial then you are saying that the tank is resting on an uneven surface and that the styrofoam has the ability to provide some amount of helping force in any area with there would not otherwise be contact between the tank and the stand.

So while styrofoam compresses, if it is to be beneficial it must have some supportive strength. (If you haven't noticed there are probably not actual technical terms, haha).

However, the argument cannot be one sided. You cannot say that it cannot be harmful because it compresses,but at the same time say that it is beneficial because it is supportive. In fact this is the very reason why it is suggested to not be used on a glass tank with trim. Now, with tiny little defects in the plane of the stand the styrofoam might be beneficial, assuming any defect is smaller than the compressed height of the styrofoam. But is there are larger defects, not large in the sense of magnitude, but large in the sense of the area of the stand affected, then the stryfoam could actually exaggerate the defect due to its ability to not only compress, but also provide a supportive force.

And for every defect it "fixes" there are two things going on. For every defect you have a high point and a low point, regardless of whether the defect is a bump or cavity. On the high point around the defect the styrofoam will compress, and provide some force up toward the tank. On the low point I guess the idea is that the styrofoam fills out the gap and provides some supportive force up toward the tank. However, the supportive force of styrofoam is directly related to the amount of compression. Highly compressed styrofoam will provide more support than uncompressed styrofoam. In fact it has to - as the compression is a function of the force applied in both direction (to the styrofoam and equally away from the styrofoam). So what you end up with is essentially a scenario that is very similar to the one created when there is no styrofoam - the high point of a defect produces a greater force on the tank than the low point. I suppose the idea is that the styrofoam can attenuate the force difference between the high and low point, but I question how much that attenuation really helps. And that help is only present when the difference in height of the high point and low point is less than the compressed thickness of the styrofoam.

Now, I am not saying that styrofoam will break your tank if you use it. In fact I have it under my tank. I think the possibility of it hurting your tank is the same possibility of it helping your tank - close to zero. Like I said, if you have a stand that really need styrofoam - I think it is better to fix the stand than use styrofoam. And even for minor imperfections I still question its usefulness.

Anyway, the short version is that stryfoam does not have magical properties.


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## Toby_H (Apr 15, 2005)

I'm really glad you made that post #6... I started writing one earlier but had to step out for a while and wasn't finding the right words... but I strongly disagree that foam is a bad idea...

So what he said ... and well said #6

I believe Glass Cages recommends 3/4" foam, which I personally feel is very excessive. I've used 1/8" or 1/4"... if your that worried about imperfections in the stand the tank is on I would suggest putting a piece of plywood beneath the tank with 1/8" foam over and under the plywood (so, a plywood sandwhich with foam bread sitting on the questionable stand with the tank on top of it all).

The "feet" on the stands in my fishroom didn't sit just right after I filled up the tanks, and these feet also hold 75 gal tanks... so I did the plywood sandwhich and they have worked great for me.

The only Con I can think of is: If you fail to apply common sense your likely to do something wrong...

:thumb:


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## Number6 (Mar 13, 2003)

Thanks Toby 

*boredatwork* ok, so I see exactly what you are saying... but! You knew that was coming... LOL

Ok, so, we don't care about any spot where the stand does not meet the edge of the glass tank. Glass tanks do not need to be supported on all edges and you can even support them solely at the 4 corners... surprising to hear, I know, but let's leave that tangent alone for another thread. 
I only bring it up to prove that we ignore a low point.

The next part you bring up is a rise in the stand where it meets a side and you assume an even rise. Will styrofoam help there? The experts say yes, because of the way styrofoam compresses, and on this we can barely speak since we are all a bit lacking on the knowledge front.

But what about smaller defects? As it was explained to me: since these cut up into the styrofoam instead of compressing the styrofoam, the styro avoids these defects creating a pressure on the less forgiving material of the glass edge. Sound like it has merit?


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## Toby_H (Apr 15, 2005)

I think I'm following you Bored... but I didn't agree with the conclusion so I may be missing something....

For example... with a large tank with a typical frame supported only along the 4 edges...

if I have a perfectly flat stand... and I have a 1/8" pebble on it... with no foam, there is a 1/8" bump 1/8" long... I believe we can both see the issue with this. It will force the tank to bow (or crack) up 1/8" at the point of the pebble, and then that point will be holding weight that was meant to be distributed along a much longer edge... an obvious potential issue

Take that same senerio but put 1/2" foam beneath the tank... I suggest that the foam will dent/compress the full 1/8" of the pebble... The compressed foam will dispurse both upward as well as outward, but mostly in the direction that the foam is not compressed (under the tank not under the edge). But actually the foam is likely to split at that pebble and not put any upward force, only outward, some along the edge, but almost all outward the other two ways, where there is no weight causing compression.

Valleys in the stand will have the same physics, but I doubt the foam will "fill the valley". But I also do not think this will be necessary as the tank will simply bridge the valley without much risk at that tiny lack of support.

Twists are the real rough part though. But again, the direction of the increased compression will be divered mostly (almost all) in the direction of the foam that is not already compressed. So foam will be less beneficial on a flat bottomed tank that is sitting on (for example) a solid table that has a twist to it's surfece. Yet although foam of X thickness will be less beneficial on the flat bottom than foam of X thickness would the trimmed bottom, foam will be far more critical on the flat bottomed tank with a twist in the table, than in a framed tank with a twist in the stand...

But this does not verify that foam creates a risk... it only verifies that twists in the solid stand are a worse case, when dealing with flat bottomed tanks...

Phew... now I need a drink... and I can't do physics when drinking... lol

PS - Bored, I read your post as a friendly debate. I hope you read mine the same way. Cheers.


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## BillD (May 17, 2005)

Toby_H said:


> Valleys in the stand will have the same physics, but I doubt the foam will "fill the valley". But I also do not think this will be necessary as the tank will simply bridge the valley without much risk at that tiny lack of support.


The foam will in fact fill the valley as demonstrated by my 4 homebuilt 30 gallon (48" x 12" x 12" ) rimless tanks on steel stands. There is roughly a 1/8" to 3/16" gap in the centre of the stands relative to the bottom of the tanks. this is inspite of my best efforts to use the straightest pieces of steel I could find. The foam compressed on the ends enough to fill the gap. The stand is open in the centre, so that only the outside edges are supported by the stand. I would in no way consider putting the glass directly on the stand without the styro. Stands that are leveled using shims and/or made of wood present the same problem, so, while the tank does not need to be supported over it's entire outside edge, putting strain on it is not a good idea.
A tank is essentially a boxed beam which makes it a very strong piece of construction. However, if it isn't supported properly, the silicone comes under unnecessary stress, which may lead to premature leaking.


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## nick a (Apr 9, 2004)

> The foam will in fact fill the valley


Perhaps cosmetically the gap is filled--structurally next to nothing is added by foam. What compresses is under load--what doesn't; isn't (still).

I will always use foam under flat bottom acrylic tanks on solid top stands (where every square inch of surface is meant to carry load). Perhaps I'd use it or 1/8"-1/4" rubber for the bare glass (rimless) tanks you have BillD, just to keep the glass off the metal. I will never bother with foam on traditional , rimmed tanks.



> If you fail to apply common sense


 and try to correct a poor stand with foam, you're behind in the game from the outset IMHO. Concentrate your effort to make the perimeter of the stand which your rimmed tank will sit on as level and flat as possible. Foam will not fix a twisted stand. If you've got bows/arcs, then add structural members to correct. If you've got 1/8"+ nubbins or protrusions, get out the sander or the plane.........


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