Mix eight ounces (0.23 liters) of pool washing compound or tri-sodium phosphate to each gallon (3.78 liters) of warm water. One gallon of this solution will wash approximately 200 square feet (18.5 m2). Dip a long handled brush in this solution and firmly scrub the pool surface in approximately 10 foot sections. Rinse off the residue with clear water immediately after scrubbing. Be careful not to allow the pool washing solution to dry on the surface. Always scrub the walls first and the floor last. The next step is acid etching.
Acid Etching - for Bare Concrete and Plaster
Acid etching is required on bare masonry surfaces like concrete or plaster. It is also effective for removing chalky residue and hard mineral deposits on a previously coated pool. Acid washing opens millions of tiny pores which allow the subsequent coating to penetrate, thus creating a secure cohesive bond. Even on previously coated pools, we heartily recommend an acid wash.
NOTE: To prevent eye injury, NEVER pour water into acid. ALWAYS pour acid into water and wear protective eyewear.