It has not been particularly problematic but every few days I have small round algae spots (black algae I would assume) that show up on the grout lines between the waterline tiles around the pool. Its typically in more shadow prone areas, corners and about an inch or two above the waterline so its not getting much contact with chlorine. What is the best preventative treatment for this? Regular brushing is what I do now but they grow back.
Brian
Brian