An 'eco-friendly' approach to metal and scale control in hot tub water. Stain & Scale 1 is added while a tub is being initially filled with cold water. It provides immediate protection against metal staining from the fill water and scale formation once the heater turns on for an extended period of time. It can also remove scale deposits that may have formed during the last cycle. It contains no phosphates and is stable in the presence of chlorine or bromine. Add the full bottle with each fresh fill for maximum protection.