Foam under tank

I've always gone stand - styro - tank. Sitting the tank directly on the styro allows it to settle evenly in place & also serves as a heat insulator.

Tank sits on styrofoam

Foam will not level out ur tank...only acrylic tank ive ever had a problem with sat on foam and it caused a leak on the bottom panel. This is a big misconception for acrylic tanks. The practice is used for glass tanks with no trim or plate glass bottom. Acrylic tanks should be placed right on the wood base and leved with shims to make it perfect. Some manufactures glue a piece of 3/4" wood directly to the bottom of acrylic aquariums to ensure they can be leveled correctly on the stand. Foam is very fragile, the corners can be damaged making the tank unlevel down the road.

Sent from my SAMSUNG-SGH-I747 using MonsterAquariaNetwork App

I don't know of a single acrylic tank maker that gives a warranty if it is not on a full sheet of plywood. Most also tell you a thin sheet of foam. If an acrylic tank isn't on a fully supported flat surface it will bow and rupture.

I always use a piece of commercial grade carpet. It's short and makes up for any minor imperfections in the stand. Best of all it's easy to slide the tank into place if you glue the carpet to the stand.

Sent from my SPH-L710 using MonsterAquariaNetwork App

How much out of level are we talking about? If I read your post correctly, you built a stand not level to sit on a not level area of floor. Why not just built the stand level and shim the stand? The tile floor where my tank is isn't perfectly level either. Probably 1/8-1/4 over 6' I always just shim the stand with no problems going on 7 years.