how close to perfect does everyon try to level there tanks? just set up my 6'x2' tank and it is perfect narrow ways and 3/16" difference in water level long ways. the stand is level and even the house is not should i care.
Your tank is pretty near perfect with it only being out 3/16 in 6'. I would leave it alone man. If you were out a 1/4" or more on the side then that would be a different story, but as is, your good to go!
Seriously, it is fine. My house has a concrete slab and it isn't even level. I just keep the water level high so that the top frame hides the imperfections.
mines on a slab also. whats funny is i built the stand in my shop which is part of a hundred year old building and its floors are level but my 30 year old house aint