You need to drain on the WASTE position, NOT the BACKWASH position. If you have a swimming pool sand filter and use the BACKWASH position you might end up losing sand in the process of draining. 2. CLOSE the skimmer valve so the filtration system is not pulling in air when the water level gets below the skimm
ength times width gives the surface area of the pool. Multiplying that by the depth gives the volume in cubic feet. Since there are 7.5 gallons in each cubic foot, multiply the cubic feet of the pool by 7.5 to arrive at the volume of the pool, expressed in gallons.
