Foam under tank

[streetrodder007]

I personally don't think your glass should bow or move that much, the benefit of foam is that it is a pliable and a slightly flexible support if you should need it, or too make up any difference in imperfections when the tank is manufactured. Foam is good cheap insurance.
I can see this moving glass issue being one of those topics everyone would argue about in different ways. Just like I don't use a skimmer- and some people look at that like I'm crazy.

[RSB2]

I called the manufacture of the tank and he said to definitely fix the gap. So I took off the plywood, which seemed to have a bow, and it fix the problem a little. All three corners are now touching the 2x4 rim (without the plywood top) there is a tiny 1/16 of an inch gap in the front right corner.from the corner out it goes from a 16th of an inch to nothing in both directions for about 2 inches. I am thinking about shimming beneath the foam. Any thoughts?

[RSB2]

I shimmed it and with the tank half full all seems fine. I spaced the shims about 2" apart.

[jay13]

Thoughts: One of two things or both are going on and I would not fill a glass box with saltwater in my house without fixing them first. 1: The tank is of poor construction and is way out of square, not likely but could happen. 2: Your stand is way out of wack and needs to be fixed or replaced. Either way you should not have to "shim" the tank between the tank and the stand, shimming should only be a fix for an uneven floor.