Pristine Blue Pristine Check is the first step and preps the water for the Pristine Blue line of chemicals. Pristine Check remove excess calcium from the water and deposits it into your filter allowing you to wash it away. Product Dosage For Pools: 2 oz per 1,000 gallons of water. For Spas: 10 milliliters per 100 gallons of water. Directions For Spas and Hot Tubs: Apply at a rate of 10 milliliters per 100 gallons of water. For Pools: Apply at a rate of 2 ounces per 1,000 gallons of water. In pools wait one day after applying Pristine Check before adding Pristine Blue. It is essential to backwash or clean the filter after the use of Pristine Check.