Hi I am new to this forum! It has been such a long time since i last had a tropical fish tank (or any at all).....

I'm setting up a new tank, its 3 foot long, not very tall (15 inches) by about 13.5 inches front to back, and not very thick glass (3/16" or 5mm). The tank has no frame, its just all siliconed together , glass on glass.

The base I want to put it on is slightly curved (not flat) with a slight hollow in the middle. There is a dip in the centre of the base, looking from the front, that curves from nothing at the side edges, to a maximum of 1/16" (1.5mm) right in the middle of the tank. There is a very slight dip in the other plane (the front to back plane) , looking from the side lower edges of the tank the gap is a maximum of between 1/64" and 1/32" right in the middle of the sides. So the tank when placed right onto the wood is sitting mostly on the outer corners, with the very middle the least supported. As far as I can tell the curvature of the base is perfectly uniform (so there is no twisting forces at all, just what you might call in photoshop "pincushion distortion".) I have read that the tank only needs support around the edges and not in the middle. But mine would have more weight on the corners and less in the middle.

Those measurements are with the tank placed directly onto the wood base.

Note that my base has no lips around the edges, so i can see and measure the gaps easily. (Its really a wall unit, solid wood, extremely strong and stable, two or 3 people could all stand on it no problem at all). If there were lips to hide the bottom of the tank (like most dedicated fish tank bases), the non-flatness and gaps would be so small you might not even notice they were there at all.

I was planning to buy a think dense closed cell foam mat to place the tank on, of say 1/2" thick uncompressed thickness, from a rubber outlet. Which i was hoping would take up the up to 1/16" of slack space in the middle of the lower outer edges of the tank.

Do you think that would be enough padding for the tank to cope?