I've spent the last two weeks pouring bleach into the pool after opening it for the spring. I've done the same thing each year for the last five or six years, and the water has always cleared within a week at most.
I've been holding the FC levels at 14-15 as best I can, checking the water every 1.5-2 hours during daylight. CC ranges from .5 to 1, and there is a loss of FC overnight. (So still killing algae.) CYA levels are below 20 (not registering) but I've been had about 6 pounds of trichlor pucks dissolved when I first opened it a couple of weeks ago, so I know the level isn't at zero.
We opened the filter and reset the sand (which was packed up all around the edges - a result, I think, of the 1.5 hp pump we used to run! I back wash the filter whenever the pressure rises 3-5 pounds, which is about once a day.
This year, the water is not clearing. When I went to brush the sides of the pool, I found them covered with a rough surface (not smooth, as expected with vinyl.) I scraped a spot with a fingernail, and got some off with difficulty. (This stuff is NOT going to come off with just brushing the walls with a nylon brush.) In looking at what I got, it is mostly brown with a bit of green, so I am thinking it is a hard growth of algae of some sort that is not completely dead (hence the water not clearing.)
So the question is - WHAT is this stuff, and how do I get it off the sides of an AG pool?