Purplish Algae?? - Stains on my Liner

Jun 1, 2011
1
I'm new to this forum, and will be trying to keep my pool clean with the BBB method once I get it clean. I opened my pool 2 weeks ago, it was pretty green. I could barely see the bottom of the 3" shallow end - (FYI 35,000 gallons IG). Lots of shock & 10 days of constant filtering and backwashing left me with very cloudy water. I couldn't see the bottom drain in the deep end. At forst I thoulght it was due to high alkalinity - was 180 - brought it down to 110. Now I have the following TC 3.0, pH 7.2, Alk 110. Based on strips (I know now- do not use), -0- FC no matter how much I put in. Per leslies- everthing is perfect, safe to swim. After finding this forum, I used my HTH test kit and found that my CYA level is more than 100. Just finished dumping about 2 feet of water and am refilling. I wil be ordering a Taylor test kit today. What really concerns me are these purplish stains that are on the sides of my liner, most of them circular. They do not come off when I brush them. I have attached a cell phone pic, since that's what I had. Is this an algae? has anyone experienced this before?
 

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Rub them with a trichlor tablet and see if they lighten. That'll tell you if it's an organic stain. If it is then holding your FC at the high end of the recommended range for your CYA will lighten them.
 
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