I am an above ground pool owner and I have had a lot of different dilemmas with my pool in the last several years of trial and error. It is an 18 ft round. My current problem has been a pretty bad case of algae. I feel that I constantly clean and sanitize my pool and I cannot figure out how I got this algae. Although, bright green is a nice color, I would prefer to never see it again in my water. So, I begin another day of battle, hopefully, I will be the victor.