leveling problem

[viperfish]

When I set up my 180 on my basement floor there was a difference of 3/8" over 6'. I screwed temporary bracing to the stand and levelled everything up, I then covered the outside gap (making a temporary form) and poured floor levelling compound inside the stand (I made the plywood bottom removeable for this reason). This stuff works great, it will automatically level itself and finds every crack and crevice. Once this dries you will have every inch of floor in contact with the stand and zero stress transferred to the tank. The levelling compound is available pre mixed and as a dry powder which you can mix yourself. I works on any surface, wood, concrete etc. The brand is Stone Mason, I bought mine at Home Depot. It was the first time I had ever used it, I even bought a trowel in case the auto levelling was a crock but I didn't need it. I thought about shims but with the weight of a 180, I wanted more uniform support. I built my stand with 2x6 and it is very heavy duty, but I still wanted it on a solid base for peace of mind.