Here's my story, (sorry for the long post)
After a citric acid treatment this spring ridding the pool of stains on my 17 yr agp, (worked very well after some time & too much citric), finally got FC to hold after 3 weeks. I've been working on tuning the SWCG in, supplementing with some bleach, starting out slow to 2 FC, then trying to get to & stay around the 5 level & have been keeping PH around 7.2. Put the solar cover on for a week, to keep the grackles from making a complete mess like they do every year when nesting. Pulled the solar cover off last Friday. Cloudy water. Still 5 FC, 0 CC. I decided enough time had past to take to shock level to clear out the clouding. One day, & the pool was very clear again. I vac'd on Saturday, pool came up to temp & I was in the pool Sunday & Monday. Thought I had it made for the summer. Clear & Sparkly, planning on adding Borates for the first time. Checked FC & PH every morning since.
Checked FC & PH Wednesday morning before heading to work. 5 FC, 0 CC, & 7.2 PH, Clear & Sparkly. Status Quo. Came home Wed nite & the pool was emerald green, still clear but emerald green! Looked like the pool walls were stained again, & with Vit C test, yes they were. Never have I had the emerald green color in my pool.
The only thing available locally here for a decent sequesterant is Iron Myte from Menards. I added the Startup dose, & now, Friday nite it is back to normal with ever so slight staining.
I did some searching on the web for my town's water test results & found an old test (don't know how old) & it listed the Copper level as 1.3 PPM. It had to be a mistake.
My son's friend works for City Hall, so I called her & asked about the latest test results on our municiple water, especially Copper. After telling me I should have received something in the mail this spring, she confirmed the level. 1.2 PPM Copper. I questioned maybe .12, nope 1.2. This is my fill water, no wonder.
Still wondering what triggered the emerald green when I've never, ever had it before, even sometimes under heavy shock load in years past, but something obviously did now. It's like someone put something in my pool that day, although highly unlikely. Obviously, it's something now I'm going to keep a very close eye on.
By the way,
CC 0 (never have tested over .5 this year)