The easiest way to get the red out is to poke a small hole in the top of the bag, and one in the bottom. Put a hose in the top and let it run. Just go away for 10 or 15 minutes, and when you come back they will be cleansed of the red. You only have to do this once. As far as cleaning them between harvests, I use a strainer and rub them well with my hands as hot water is pouring over them. I know this is wrong, but I've never PH'd my rocks. They are supposed to be more PH friendly than other mediums.