ive had sand for a while, but im getting rid of it now, coincidentally i started syphoning it out today. if you choose sand, you need to put so thin of a layer that it really just covers the bottom of the tank, if its even an inch thick, its WAY too thick. what happens is that the sand traps nitrites/nitrates and if a certain patch of sand is left untouched for too long, upon disturbing it, it can actually create sulfuric acid in your water, instantly dropping your pH to 4 or lower and doing massive damage to your fish (obviously). Get rid of your sand if you have it too thick, or simply take enough out so that you are only covering the bottom of the glass.
Believe it or not, sand ends up being MUCH dirtier than gravel and very annoying to clean. Best way to clean it is to syphon the sand into a bucket and actually washing the sand off, then dumping it back into the tank. Even then, it should be done every 3 weeks.