How level does my 400 gallon acrylic tank need to be? I filled it up with water last night after getting it set up and all the plumbing done, and the water level is off by 1/4" to 1/2" from side to side. Does it "HAVE TO" be perfect or can there be some forgiveness. I have it on its stand which is on a concrete floor in my garage with a peice of carpet between the floor and the stand(intent was to help with leveling).