Never use your spa without first testing your spa water. The ideal chlorine level is between 3 parts per million (ppm) & 5ppm. Rapid dissolving chlorine granules for hot tubs and pools from Relax. As a general guide to increase a 1500L hot tub from 0ppm to 4ppm you will need to add at least 12g of Relax Chlorine Granules.
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