Swimming pools provide relaxation and a place too cool off but not when their waters turn green. Pools require a lot of maintenance to keep clean and the water fresh. Algae are the most common reason for swimming pools turning green, and occur when there is not the right concentration of chemicals in the water. Preventing algae is the first defense in keeping blue water all season long and it requires weekly maintenance and cleaning.
Check your pool water levels three times per week to ensure that they are inhospitable for algae growth. Keep chlorine levels at 15 ppm, stabilizers at 60 to 70 ppm and pH at 7.2 to 7.8 (see Reference 4). Adjust alkaline and acidity by adding a base or acid, depending on which way the water needs to go.
Vacuum the base of the pool several times per week to pick up loose debris, dirt and algae. Use a pool net to pick up floating bugs, debris and other items that have entered the pool. Scrub the sides of a pool using a pool brush to break up any loose debris and dirt for the vacuum or net.
Set the pool filter to "waste" mode to help filter out any dirt or debris left in the water in preparation for a chlorine shock, once a week after a cleaning session,
Purchase chlorine-shock tablets at a local home-improvement or pool supply store. Use shock tablets once a week following a cleaning session to kill any contaminants in the water and remove any algae attempting to grow. Follow the directions listed for any pH adjustments required for the water --- some manufacturers require a specific pH level before using a chlorine-shock tablet. Prepare tablets according to the instructions; most require you to dissolve the tablets in water before placing them in the pool.
Turn on the pool's filtration system and slowly pour the water and chlorine-shock mixture in front of the return line fitting --- this will help disperse the chlorine shock throughout the pool. When there is ¼ of the mixture left in the bucket, remix it with water to pick up any undissolved particles, and slowly pour the remainder into the pool.
Allow the chlorine shock several hours to work before testing and readjusting the levels of the pool water to safe concentrations. Repeat this process once a week to prevent algae growth and keep the water blue.