The Gold Horizon Spa revive is a fast acting, dual action clarifier. This product has very minimal effect on the p H level of the eater & is a great product to use for regular oxidising of the spa water. You can add the Spa Revive directly into the Hot Tub water & leave the pump running, with the spa cover off for at least one hour after the application. The ideal recommendation of this are 35g of the Spa Revive per 1, 500 litres of spa water.