Foam under a SeaStar tank?

[Dradee]

This Seastar tank has about a 1/8" lip on the bottom from the decorative trim which you can see from the picture of the pink insulation it sunk in about 1/8" all around the edge.

The stand top is level but the pink insulation I used was wavy and uneven BUT I thought it would flatten out and conform to the tank bottom but now looking it never really did. You can see in the pic of the foam that the scratches,nicks and dings in the foam did not even flatten out from a 1400lbs of weight.

This building insulation foam is very high density and does not want to conform at all. I also cut the foam totally flush with the tank after it had settled full of water/rock.

My theory is the pink insulation sunk in around the edges more pushing up in the center of the tank unevenlly putting a slight bending up force in spots now couple that with rock all down the middle, a wave maker and 16 months later, maybe even a slight flaw in the glass and it finally gave way and cracked.

I will never use this high density pink crap again! Weve had tanks for ever and always used low density foam carpet underlayment and it conforms very easily.

This is the product we used,Owens Corning FOAMULAR® 250 extruded polystyrene insulation
http://commercial.owenscorning.com/f...mular-250.aspx

Originally Posted by StirCrazy

now allot of this just doesn't make since at all... if your tank is a standard sea star tank there is about a 1/4 to 1/3" lift from the edge frame. if you are using 1/2" pink foam it will compress about 1/8th of an inch under load and the center glass should never touch the foam anyways. for the foam to cause a problem even if it is touching the center of the glass you would have to have a stand that is pretty far screwed up and not at all flat with weight on it.

there is one concept here that people are getting wrong, you have the exact same amount of weight (Pressure) pushing down on the whole bottom, weather it is in the middle or the edge.. pressure which is a force is influenced only by the the matter above it. I think the problem people have with foam is mostly caused by trimming it to close to the tank allowing the edge to collapse more than the middle, or thinking foam can adsorb more irregularity than it should.

the very edge will have the most weight as the density of the glass above it is higher than that of water so the edges should sink more. for instance I had a slight depresion in my foam around the edge like shelly's picture shows but the middle glass never touched the foam as pink won't compress that much

personally I think drilling the bottom would be a bigger cause of a break than it touching the foam as drilling a hole in it severely weakens the panel of glass thats why I always drill the back or sides of my tanks.

Steve