I've been dealing with this issue since lthe end of last pool season and I haven't been able to figure it out.
22k gallon 30ft round vinyl liner above ground pool.
For starters I used pucks last season and made the switch to liquid chlorine this season. Half my pool drained out over the winter because of a tear in my vinyl liner when I was closing (dropped the weighted bucket for the stairs. I didn't notice it till I reopened this year. Hole is now patched. ). Fortunately that let me get my cya back under control since I had to refill. In any case I have been slamming at 10-20ppm chlorine for the last week and I still see these black streaks everywhere.
They disappear when you brush the pool, but come back less than 2 hours later. Almost looks like sediment resting on the creases of the liner. Not sure what to do anymore besides continue slam, but it's getting expensive.
22k gallon 30ft round vinyl liner above ground pool.
For starters I used pucks last season and made the switch to liquid chlorine this season. Half my pool drained out over the winter because of a tear in my vinyl liner when I was closing (dropped the weighted bucket for the stairs. I didn't notice it till I reopened this year. Hole is now patched. ). Fortunately that let me get my cya back under control since I had to refill. In any case I have been slamming at 10-20ppm chlorine for the last week and I still see these black streaks everywhere.
They disappear when you brush the pool, but come back less than 2 hours later. Almost looks like sediment resting on the creases of the liner. Not sure what to do anymore besides continue slam, but it's getting expensive.
That does look like your standard algae, not black algae. Since your CYA is 50, the SLAM FC level to maintain would be "20". Doing your best to maintain that proper FC level during the SLAM and following the