Hydor Magi-Klean Pump & Accessory Cleaner safely removes lime/calcium deposits from pumps, filters and aquarium accessories. To use, just add the contents of one packet to 1/2 gallon of clean water in a bucket, allow Magi-Klean to dissolve, soak the equipment in the bucket for a couple hours and then rinse thoroughly before returning the equipment to the tank. For heavy lime/calcium deposits you may need a longer soaking time and the assistance of a small brush.