Aqua Safe is a pond water conditioner and DE chlorinator that's essential for all pond keepers. Standard tap water contains chemicals and metals that can be harmful to pond fish. Tetra Pond Aqua Safe quickly eliminates chlorine and chloramines and binds and detoxifies heavy metals. It converts standard water into "pond water" so fish and plants can flourish. Tetra Pond Aqua Safe contains iodide for more vitality and readiness to spawn. This liquid formula also provides a colloid coating to protect sensitive fish gills and membranes. For outdoor ornamental ponds only. For new ponds or whenever adding tap water, use 10 mL for every 50 gallons of tap water, or use 1/4 cup for every 300 gallons of tap water. To calculate pond gallons, use the following formulas: length in feet x width in feet x average depth in feet = cubic feet; cubic feet x 7.5 = pond gallons. If chlorine levels in your tap water are high enough that you can smell the chlorine, use up to double the standard dosage.