Maybe a hose with a good attachment. I would not recomend a carwash because of the soap. The idea is to get out any dust , dirt, or dead critters out of the rock before you put it in your tank. Some people will bake it in the oven after that just to make sure there is nothing but the rock added to the tank. The less contaminates, the less the cycle of the rock. Once it is added to the established tank all off those animals, the pods and stuff will have more housing to multiply into.