yes we have had algae!! And it has been horrible to get rid of. I think it was because we went on vacation and it was stinking hot. Then it rained 2 inches so the chlorine and chemicals were out of whack. We've shocked it and used a lot of algaecide. I asked my husband did you use flock and back wash it? I knew we had some but he said we didn't. So I got it out and he flocked it. And the green particles dropped to the bottom. He had to put more water in as he was vacuuming to flush. He did this Friday and it is no longer green but a little cloudy. Labor Day is coming and he is so ready to close it up.