Algae won’t go away

So I was gone over the weekend and had my husband add chlorine in morning and evening. He doesn’t do testing so I just went with what I have been adding. Only thing that has changed is looks like the spots in morning seem a darker color than used to be. And just this morning, I wondered if algae could possibly be on the bottom side of the drain cover??

Tests this morning are about same as last week:

FC 13.0 ( adjusted to 16 after test)
CC .5
pH 8.0+
TA 125
CYA 40
 
Using Taylor K-2006 test kit

Was testing 4 or 5 times/ day when started SLAM, now usually just morning and evening.

Using liquid chlorine (12.5%) unless I run out then use Walmart’s pool chlorine ( supposed to be 10%). I do change value on the calculator according to which percentage I’m using at that time. Our nearest pool supply is an hour away which I need to go there again today. Also been using Clorox powder chlorine stabilizer since my liquid conditioner order is on back order and pool store price is crazy
I do not know how knowledgeable you are so take no offense but be wary about the liquid chlorine you buy, make sure it's fresh. I sent my friend to pick up several cases for a slam and he picked up 4 at a local hardware store (in fairness I sent him there not having checked them myself first) and after checking the dates they were made in January of this year. Needless to say we took them back, the employees don't know any better.

If you need help determining the date google or post here I'm sure you will get the information that you need.
 
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