Since I began to notice some algae collecting in certain spots late in the week, I tend to agree with you and Waterbear on the algae bloom. If I can believe pool stores, I've never had an issue with iron before. I am not on well water. By my math I caluclate for 26000 gal, I need to add 1 gal of chlorine to increase 1ppm. Does that sound right? Is there a limit to how much I can add at one time? Thanks for the help