I have a 29gallon biocube. When I was setting everything up the tank was almost perfectly level. Now it is filled with water, 40lbs of sand and around 30lbs of rock. It has been about 2 and a half weeks and now the tank seems to have settled a bit and it is slightly uneven (the tank is on carpet btw). I shut the pump off and measured the water level and it seems to be roughly 3mm lower on the front left than the front right? Is this significant enough to stress such a small tank? What should I do, if anything to fix it?