So I have been trying to level my tank with plywood, I put 2 pieces of 6mm plywood under the 2 legs of my stand and its off level by about 3mm still, I am worried because it was my bf who cut the pieces of wood and they were badly cut like not straight and odd sizes, i heard that shims that were different sizes were bad to use but we were quite in a rush and also couldn't find proper shims anywhere, the tank is filled not and not sure what to do Its a 57 litre tank if that helps. Should I just remove the pieces of wood? The tank is more level with them so worried removing them wood make things worse.