Help with stain removal and metal free

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I added a quart of Polyquat 60 yesterday and my numbers were:
CYA 35-40
FC was 5
Ph 8
TA 140

Today's numbers were as follows before -the Ascorbic acid and Jacks metal free
CYA 35-40
FC 3-4
Ph 8
Ta 100

I think I messed up. I used 4.5 lbs ascorbic acid to 26,000 gl vinyl liner pool to remove stains. My water was going through the sand filter the entire time. I had asked DH to put on circulate only, and he misunderstood. About an hour, the stains were gone. Then we realized that the filter was running, so we backwashed the sand.

Then we added about 2 quarts of Jacks' Metal Free with water again running through the filter.(?) Double dumb? Anyway. about an hour later I have no fc and cannot get enough Dpd powder in the vial to turn the sample pink. The ph came down to 7.3.

My stains are gone! Doesnt the Jacks Metal Free sequester the loose particles? Will they get caught in the filter then? Do I need to add any other sequestering agent, if so what? Do I need to change from filter to circulate only?

Thanks for your help!