I have just repaired a small leak in a 15 gallon tank, successfully! (thanks to advice I got off this site) Now my strange question is..............I was going to put polystyrene underneath it to ensure even surface, but find that the bottom of the tank does not come into contact with the flat surface I'm going to put it on. What I mean is the bottom of the tank is fitted in about 1/4 inch up from the bottom of the sides so that it creates a gap between flat surface and tank bottom and then there is a thin plastic surround that the bottom of all 4 sides fit into (hope I have explained this ok)

What concerns me is that the bottom is not supported by any flat surface, only by the sides of the tank itself, will this be enough? I know the tank was built like this so it must be adequate but it worries me (especially as I have done a repair) and just thought that all tanks sat flat to any surface they were put upon

Sorry if this sounds stupid but would welcome some reassurance from anyone that this would be ok. Family and friends think I'm being paranoid but they don't know anything about tanks or fish

The tank is designed that way - the glass is supported by the frame. The frame takes the weight.

As a leveler - you want to make sure that all the sides of the tank's frame are supported all around and level. The glass, itself, will be taken care of by the frame.

I place the foam down such that it extends a bit past all the sides of the tank's frame. Level it with a level, and set the tank on it. The weight of the tank will further level itself.

I like to wrap patterned fabric around the foam - since I run barebottomed, I put rock print fabric downt here.....

The fram will be fine as long as it is not cracked, split or twisted.