Brush the pool walls thoroughly, especially those areas with visible algae blooms. Be sure to use a brush that is safe for your pools. Wire brushes are great for plaster and gunite pools, but should never be used for vinyl, fibergl., or tiled pools..Scrubbing the algae off your pool walls lets your sanitizer get deeper into the remaining algae. It also stirs up the sediment you’ve brushed off so it can be killed and filtered out. Using a stiff pool brush If you click this link and make a purchase, we earn a commission at no additional cost to you. on a pole, brush the walls and floor of your pool..After the pool filter has been running for hours, examine the pool. Dead algae turns white or gray, and either suspends in the pool water or se.es to the floor. Whether or not the algae is dead, test the pool again for the new chlorine and pH levels..The causes of pool algae growth include Inadequate, free and available chlorine levels caused by a heavy rain, a lot of swimming or poor maintenance Too high of a pH level, preventing chlorine from killing the algae Insufficient cleaning or brushing of pool surfaces, leaving the surfaces dirty and vulnerable to algae growth.