Direction for use: A non-polymer filter aid MUST be used in sand filters with this product 1. Add 1lb of Stainfree per 10,000 gallons (38,000L) of water. With the filtration system on, walk around the pool and sprinkle the product evenly on the surface, brush stained areas. 2. One hour later, add METALfree to pool water at the rate of 32oz (1L) per 20,000 gallons (75,000L) 3. 24 hours later, pool must be thoroughly vacuumed and the filter cleaned 4. Test water and balance water if necessary Important: DO NOT shock pool for one week. If chlorine level is low, add small amounts of chlorine. Do not exceed 2ppm.