Foam under a SeaStar tank?

[Borderjumper]

My tank just cracked. The bottom cracked from one corner length wise in a big S all the way to the opposite corner.. For the full 4 feet.

This is.. Well was.. A 18 month old 4ftx2ft old Sea Star tank made with 1/2" glass.

We put a piece of pink insulating foam under the tank.

We just took the tank off of the stand and it looks like the edges of the tank compressed the foam slightly.

What Im wondering..if the edges compress, this is basically lowering the bottom glass until it contacts the foam. This foam is pretty rigid. I'm thinking that with the edges compressing, more pressure was being put on glass.

Looking at the bottom of the tank, it looks like the frame is slightly higher than the glass bottom.. But only a fraction.. I'm thinking the tank is made so that the edges carry all the weight and the bottom basically "floats" for a better word..

So if the glass is supposed to float, with no pressure on it from the stand are we screwing this up by letting the tank sink into the foam causing the bottom to make contact, which makes it suddenly bear weight?

Thoughts? And does anyone know if a seastar tank is designed so that only the frame carries weight? I remember tanks from when I was a kid.. They used to sit on those old metal stands that were only frames with nothing in the middle.

[Gooly001]

Hey Shelley,

Eugene and I had a discussion to find out how you achieved the crack on a 18 month old tank and we concur that it was the foam that may have caused the crack. Tanks with trims that leaves a gap underneath the tank and stand surface are designed to sit directly on the tank stand surface. If the trim is allowed to sit on foam, the slight difference in pressure may cause stress on the bottom pane and eventually crack. This is just our opinion but I would agree that the foam caused the crack.

Cheers,

Paul

[Mrfish55]

Could be an uneven stand causing the tank to twist, could also be a defect in the glass that just took that long to let go, I have seen a couple of virtually identical cracks and when the stand was checked for level, they were both found to have warped tops (both commercial stands) The foam underneath should not have made a difference, I as well as many others have used foam without issue. I don't know if Seastar has improved the build quality but I know the local shop quit carrying the line many years ago due to the failure rate. Hope you are able to get going again, you had a very nice setup, good luck and Merry Christmas.

[Aquattro]

Shelley, have you called SeaStar and asked them? Progressive has all their tanks on the same foam, I'd hate to see the store go pop!! I'm wondering if the wavemaker had anything to do with it?
My 90 is a SS but I had it on a foam underlay type of material. My 155 was also seastar and sat on foam for years.

[Borderjumper]

We will call seastar next week.. No one was answering today.

The foam theory does make sense to me. That pink foam has very little give to it...it's really quite hard, and the bottom of the glass was pressed into it pretty hard which is what held the glass together and slowed the drain down to a dull roar.

I've got foam under all my other tanks, but it's the much softer grey underlayment kind.. Not this rigid pink insulating foam.

the wavemaker I guess could have contributed... I sure would feel much better if I could pinpoint the cause.

[Aquattro]

Originally Posted by Borderjumper

I sure would feel much better if I could pinpoint the cause.

That's tough. Lots of people use foam, and lots use wave makers. The foam theory does make sense though. How much compression was there? Enough to force the contact between glass and foam? Thinking back, my 155 sat on a framed stand, no solid top so foam only contacted the edges. I never sit my tanks on a flat surface, so foam would work fine for me.

[Borderjumper]

Yeah the glass was defiantly sitting down onto the foam.. The edge of the tank had compacted down into the foam at least an 1/8 of an inch, putting the glass right on the foam,that's why the water didn't just gush..the foam was exerting pressure kind of holding it together. If a tank is not designed to have the glass carry any weight, and it's in contact with rigid foam.. It's carrying weight. If it woild have been soft foam.. Then I would think it would have just kinda of supported the glass.. Hard foam has no give.. So the glass was actually being pressed down on it..

Foam and the pink insulation foam may be two different things in this application?? Think of the foam floaties that corals come on.. It's hard and doesn't have much give.

[Aquattro]

Sounds like you've got your cause then. Still crappy!!

[Borderjumper]

heres a picture I took of a piece of the foam we removed.. it may explain better than I can in typing.. see how the rim sunk into the foam all the way around, leaving the glass in contact with the foam. The farthur the rim goes into the foam.. the harder the glass presses into the foam.

[imisky]

hey Shelley,

It was quite a shock when Paul told me about the tank, so as Paul has mentioned tanks with floating bottoms should only be supported by the trims and should never be put on foam in any situation. The result is usually what happened to your tank This is usually the case with tanks built with the 4 side panels sitting on top of the bottom glass. These shouldnt sit on foam as any pressure on the bottom will push onto glass that doesnt give much before snapping or in your case cracking.

Tanks thats built with the 4 side panels sitting around the bottom glass has a little bit of a flex if theres any pressure pushing up on it as the silicone holding the bottom panel to the 4 sides will flex as the bottom pannel gets pressure.

Hope that makes sense

Cheers,
Eugene