Advice? uneven tank

Is the floor under it level? What kind of stand is it, meaning, what type of construction? This to me is a big concern because I've been on the the bad side of this issue and now I have a big bar clamp on my tank.

Pictures would really help

 

No, not on a rimmed tank.

Is it glass, acrylic, rimmed, rimless, etc

 

Yeah you need to remedy that. Your top bar is not completely flat and even. Is your top screwed/glued down to the 2x6 frame top members? Likely, the top members are not planed flat and level (which is a bit difficult to get perfect)

If you can disconnect the top panel and plane a bit off the 2x6s, or add shims between the top of the 2x6s and the flat top to bring it into full contact, that's what you need to do. Bottom line is that you need full contact with the bottom trim/frame all the way around.

You can also just add shims under the tank as you have it (between tank and stand) but that will be visible, obviously. I use cedar shakes, $15 for a huge bundle at Menards, which will be various thicknesses including paper thin

 

Well since it's a glass tank, there are a few possibilities here:

- the rim of the tank was not siliconed in just right and it's actually pushed off the tank everywhere except that one area (where the trim IS in full contact with the tank)

- The stand looks like it is perfectly flat, but it's not. The tank is though.

One way to see is to put the tank on a flat concrete pad like a driveway or garage, etc. Then you will know which one is telling you the truth.

Either way, I think the answer is to shim it. If you want to cover that up, then get some quarter round and match it up maybe?

 

This is not correct - you should never, ever put a rimmed tank on a full sheet of styrofoam. The reason is that the trim is not designed to be supported anywhere but the very bottom. The styrofoam compresses and puts pressure on the glass bottom of the tank, which will crack it. This is especially the case if you have a tank with one or more center braceslike a 75, 90, 120, etc, but it's equally the case with a smaller tank like a 40B. I've seen this happen many times (online).

That being said, if you have no other reasonable chioce but to use foam, you need to cut it so that it is only in contact with the bottom (perimeter) of the tank frame. Either in narrow strips or one big square that is hollowed out.

 

If you put a rimmed tank on a stand that only supports it by the perimeter, like most stock stands, then you're probably OK because the foam isn't supported directly under the center brace so it doesn't push up the full span of that brace - but it does, a bit, at the point where the center brace meets the perimeter. Don't go tearing your tank down to fix it, just don't do it again. Rimmed tanks are not designed to be supported like that.

If you put a rimmed tank on a flat plywood surface with foam on top, IMO you're asking for disaster but that usually happens shortly after you set it up. Rimmed tanks, especially with a center brace, are not designed to be supported across the center brace with upward pressure. They are designed to distribute the weight of the tank and contents to the perimeter. When the weight of the tank pushes down into the foam around the edge it compresses most easily here, and then the foam pushes up on the center brace, which can crack out the bottom panel.

The braces are only there to keep the trim from popping outward. I've put a 40B on foam but that was because it was sitting on my basement floor which is sloped for drainage, plus a 40B only needs support on the 4 corners and it not heavy enough to compress blue foam (and it has no center brace).

Blue or pink foam board doesn't compress easily so that's the saving grace, but that also means that when it does compress around the edges, it could push up with more force in the center.

White styrofoam compresses very easily and would push up a little more evenly but that's just as bad, and if the tank is heavily loaded (or large, the larger the tank, the higher the compression with just water in it) then you get into pushing up on the glass by the foam as well.