Sand is way better but MAKE SURE you use a thin layer you only wan't like 1'' of sand or even less thick sand is a PAIN to keep clean and also pockets of gas can form and be very harm full to your fish plus you can't vacuum sand like you can gravel it will get sucked up what you do is useually all the waste stays on top of the sand you just skim the gravel vacuum over the top layer and suck up all the waste on top if you stick it down into the sand like you do with gravel it will suck you sand right up