I got mine from a pool supply store for like 10 for a 50lbs bag. I used two for my 125 gallon. If you are getting good stuff you really will not have to clean it much and it shouldn't cloud your water at all really. I know some people say that playground sand works too but it is much dirtier and will have to be cleaned very well and even then you are going to most likely get clouding. Good luck.
-Cage
-Cage