Once a month add 2.5 lbs of potassium permanganate to the feeder tank. To add the potassium, remove the lid on your feeder tank and pour 1/2 of the 5lb container. A 5lb container of potassium should last approximately 2 months. In order for the system to function properly it is critical to maintain enough potassium in the feeder tank. To check if there is enough potassium in the feeder tank, insert a small wooden stick into the mixture. The stick should be stained a deep purple. If the stick is light pink or has no color, you must add more potassium.