Wow you guys are amazing. As a first time pool owner, finding this site before installation was a blessing.

We had our pool installed just over a week ago. (16x32 vinyl lined IG). Initially, it was only partially filled and we now have a greenish ring around where that initial waterline was. You can't feel it and can only see it if you are specifically looking for it, but it drives me CRAZY. My friend suggested trying a scrub brush as the vacuum doesn't help at all.

Yesterday I had a test done at the pool store and left without buying the oodles of chemicals they insisted I needed. I did buy CYA, but only 6# rather than the 12 they recommended. I added about 4# yesterday and it is completed dissolved tonight. This is the only chemical other than bleach that I have used. I just opened the Taylor 2006 test kit and have these results:

TC 7.5 (I added 3 gallons of 6% last night as water was looking cloudy and we were previously without any stabilizer. Pool store wanted me to add 5 gallons of 12%)
CC 0.5
PH 7.4
ALK 120
Ca 120
CYA less than 30 (but the dot does disappear before the top of the vial)

Any advice on clearing the CC? Eliminating the ring? Should I still wait a week before adding more CYA?

Thanks so much for your help