I have read as many mustard algae threads as I could find but I am stumped, maybe I am overlooking something.
About a month ago I could see a dry yellow ring around the entire pool above the waterline and with the rake I could scoop up a bunch of yellow stuff. Wow, what a year for pollen, I thought.
Not pollen, but algae says the pool store. I then went through some things that didn't work: 8 pounds of shock poured through the skimmer; Yellow Treat; "Heavy Duty" algaecide. This emptied my wallet. The problem kept returning. Money for nothing.
Finding this forum, I obtained the TF test kit and 48 pounds of 73% hypochorlide. Have gone through 28 pounds of the stuff. There is no equipment in the pool, no lights and no ladders. I've brushed all surfaces repeatedly, including the walls and floor even though I've never seen any algae on the walls or floor.
I could never adequately thank the many posters for the advice that is available her. I'm posting now because I am stumped.
Having kept the FC at above 44 for a few days, I'm now at FC 35 and what do I see? Some dusty yellow something-or-other mixed with grit around the water line. I wipe it with a finger and it rolls up into a brown mini-lump, with a little bit of grit. It is not slimy. Some of the yellow has a bright yellow core, about a quarter of the size of a grain of rice, surrounded by a thinner skin that extends outward, like a fly's wing, only yellowish.
Here are today's numbers:
CH 710 (did this twice, is this a number in the realm of possibility?)
The sand is 3 years old.
What is this yellowy stuff that is ringing the water line of the pool?