algae growth

Hi, Kurt, and welcome to the forum!!

The best and most foolproof way of preventing an algae bloom is keeping adequate chlorine levels in your pool. Since you see algae starting to form already, you need to shock the pool up to 15 ppm of chlorine. You need to KEEP IT THERE by testing and adding more chlorine to get back up to the 15 ppm, and do this 2-3 times daily, or as often as you can. In a pool your size, each 2 quarts of 6% bleach you add will raise the chlorine by 1 ppm, so you can use that as a guide when figuring out how much to add. The more consistent you are about maintaining that shock level, the quicker the algae will die. While you're doing this, keep the pump/filter running, cleaning it as the pressure indicates, and brush the pool at least once daily to dislodge any algae stuck to the walls and giving it greater chlorine exposure. Keep your chlorine at 15 ppm until 1) the pool clears, 2)your CC is 0, and 3) you lose less than 1 ppm of chlorine overnight when measuring after the sun is off the pool in the evening and then again in the morning before the sun hits the pool. After those 3 conditions are met, you can let the chlorine drift back down, but it should NEVER be lower than 3 ppm. It's letting the chlorine get too low that's causing the algae.

Janet