Nightmare vacumning sand compared to the sheer satisfying ease of gravel, you'll probably suck some sand up every time and as already said you'll only be able to skim around the surface and unfortunately not be able to perform a proper deep clean of trapped mulm and detritus. Plants are the way to go for sand lovers, where the nitrate greedy roots help take care of things below substrate surface. When you're dumping the vacumned water, it's a bad idea to pour any sand you've sucked up down the sink or outdoor drains where it will accumulate and cause probs down the line.