Tanks size was mentioned in the OP.The size of tank would help... I've seen smaller tanks completely out of level full of water for a long time with no problem (not saying its good)
I've never used foam or rubber Matt's
I didnt mean matt or foam to level it out but to take stress off of one part off the tank.. a shim your placing weight on 1 small area a matt it distribute throughout the whole tank... it may even slightly level out the tank... I can tell by his picture how far out the whole tank is... I asked what size the tank is and dont think hes responded to that... different if its 55 gallons or 300
I wouldnt put foam under any sized tank but appreciate the suggestion
