I used the black sand twice in a 10 gallon tank, and both times I only rinsed the top layer, not the lower ones. The last time I used a big collander type insert for a pasta cooker, that is about 2 gallon size, I would guess. Then I bought a yard of a polyester, very fine mesh netting at a fabric store, about $3 worth as I recall, and put a double thickness of that in the collander. That let me run water through the sand in pretty big batches, with no problems at all. And, only slight cloudiness in the tank, later.