yellow-brownish stains

opened my pool as i've done for ten years shock as usual water became green . my test were.TH-100 TC-10 FC-10PH-6.8 TA-40 CA-0-30 pump ran 2 days ,got my water tested at the store ,water was basically the same saturation index. -1 TDS 200 CYA- not tested TC-8 FC -8 PH-7 demand drops-6 TA-60 Adj.TA 60 TH-150 optimizer= not tested copper- 0Iron. -0.1 Manganese no cloudy- hazy green algae-none black A.-none mustardA.-none Slime mold -no. so the guys says maybe the stains are mustard A. that it grows in the liner???? and my metals aren't high but try pool magnet plus.....then i need 21 lbs. to raise my alkalinity ????
what Idid was put the required dose of Algae Kill (6 oz.) in . waited and brushed and brushed. to remove the stains... water did get alot better back washing was very yellow . but my stains are still there
so i'm thinking it is the Algae should i keep putting MORE algae Kill in or maybe shock again Hey between you guys and some comon sense i've handled and fix all prblem in these ten years but these stains got me stumped:(