METALfree is a highly effective metal chelating agent that protects against staining and discoloration from trace metals such as iron and copper. METALfree should be used as part of a well designed pool maintenance program. METALfree does not raise phosphate levels in pool water like many other stain and scale products. METALfree Instructions This product is designed for use in properly balanced pool water. Initial Dose: Add 1 bottle (33.9oz) per 20,000 gallons around the perimeter of the pool. Weekly Maintenance Dose: Each week, add 1 capful (4 oz) per 10,000 gallons around the perimeter of the pool. Note: Take caution to not spill or splash METALfree on deck or coping. Do not use with biguanides. Important: METALfree works by keeping metals in solution so they are unable to stain pool finishes. It does not physically remove the metals from the water and therefore will not affect metal readings on water test results. 1 Buy = 4 Bottles (1L Each)!