But your sand in a bucket (half full at a time), put it into your bath tub, take the shower and rinse the stuff turning it round and round with your free hand.
I know it sounds stupid to wash sand, but that is how you take all the fine particles out. Same with gravel.
I might sound like an :ufo:but it works. That's what all the aquariopeople I know do. Wash gravel and sand before you put it in the tank.
If you have a garden, take the bucket outside and use the hose.