This is my first post, but I have been lurking here for years. I want to say thank you in advance for the help this forum has provided over the years as I am sure it has saved me hundreds in pool chemicals! I will try to keep my post brief and upload pictures later this week if needed.
Problem - Algae on stairs - Black in cracks and pits on the (fiberglass?) stair case?. This stuff will not die (if this is the problem) and if I let my chlorine drop below 10ppm I start seeing a brownish/redish slime on the stairs.
Treatment - when I first opened the pool this year, I swore I would beat down the stair monster and I nuked the pool for 3 days at 50+ ppm.
Current Pool Status - Blue sparkling water - just totally annoyed with the stair monster
CYA - 80-90
Alk - 90
Salt - 2700 ppm
Calcium - 400 ppm
Borates - 50ish ppm
FC - 23 ppm
CC - 0
Sand Filter with DE alternative added for better filtration
Chlorine Method - Liquid 10.5% Bleach only unless away for extended period then I add Trichlor pucks, I don't have a chlorinator
Polaris and 1.5 hp pump
Any advice you can give will be greatly appreciated!