How would you level it?? 54G corner

[PPBlimpy]

Unfortunately shims are your best bet. You can get tapered plastic furniture shims. I won’t say that 5/16 is extreme but that would be enough to bug me.

My floor was out 1/2” over 36”. The cons of owning a English built house(1759)

I built the platform and put it on adjustable feet. This allowed me to level however I needed and also raised the tank 2”. This tank is short so I like the added height