Soak in a 1:1 bleach:wate rsolution for 24 hours in a non-metallic container in a well ventilated area and away from children. Rinse well, then soak for 8 hours with a solution containing 2 tablespoons of ChlorGuard , Prime, or equipvalent dechlorinator per cup of water. Rinse well. For freshwater use, soak for 4 hours with a solution containing 1 tablespoon of buffer per cup of water (discus Buffer, Neutral Regulator, or Acid Buffer). Original color and full activity should now be restored and Purigen is ready for reuse. Caution: some slime coat products may permanently foul Purigen and render regeneration difficult. Do not reuse if odor of chlorine is detectable. In case of doubt, soak beads in small quantity of water and test for residual chlorine with a chlorine test kit. Do not taunt happy fun ball.