Pool opening - unsure if Black Algae-HELP

[Watermom]

gfritz1,
Click on the "edit my signature" tab in my signature below and you can fix your signature line.

Also, I believe Carl meant CH level 200-400 in his post above instead of 200-40!

[gfritz1]

will do now facing a bigger problem .When starting my Hayward unit this year the pimp started yard .Had to give it a little tender loving tap. It was purchased in 2008 which was my 1st replacement .It sounded loud so ordered a replacement motor Sunday .Today while staining the pool deck it died . New motor will be here late Wednesday ,When it rain it pours. Grandchildren coming home for Memorial Day so pressure on !

[gfritz1]

Ok PH is down to 7.6 and chlorine has been elevated for three days . Today added Poly Quat 60 by Kem Tech . In working on pool the last week the stain is getting better but far from gone .Hopefully On Sunday can actually get in the water and be more aggressive with brushing and et better idea of what is going on. I have noticed the following :
1.If I take shock and put in sock and set on the stain it removes it . I tried in numerous areas and t lighten or removed in all areas
2.I had some ascorbic acid from last year and when did the same sock trick it also lighten it or removed it

Is it possible that what I have is a huge metal stain on the pool ? Makes no sense why only on the deep ends but? I had have had metal stains in the past and last year went through the metal removal process with success .But I hear stores where it can come back worst then before?

[gfritz1]

Some Corrections - 1 >ascorbic acid "does not remove the stains" that occupy the majority of the pool . (2) Confirmed again this morning that the HTH calcium hypochlorite "does completely remove the stain"
I went to work on the fiberglass steps this morning to conduct my test and thus am now based on everything you said confirmed it is a "organic stain " that is causing me the concern .
We have had a extremely wet spring in Pa after a extremely hard winter .The water table is as high as I can recall and water is laying in my yard places it never has in almost 40 years . Have to assume much water behind my liner on the inground pool .
Check readings this morning and update PH 7.4 FC 11.5 CC0 TC 11.5 Alkalinity 120 and Hardness only 100 . Concern is that CYA is creeping up with using the powder HTH as now at 60 and with history of chlorine demand really hate to use the HTH . Line is within a year or two of replacement and is badly wrinkled in spots so by no way is it "smooth" . I ended up with water behind the liner and when sucking the liner back and removing the water it was left wrinkled or high "PH" has taken toll?
So have so far super shocked and kept chlorine levels high. Brushed and vacuum ever day . Treated with Poly Quat 60 yesterday . Any suggestions other then brush and vacuum? I really like the results of the HTH in a sock and going after the dark spots as it really is like instant clean but again worried about CYA ? Waiting for your expert opinion

[Watermom]

Cal-hypo does not have CYA in it.