Help removing slight brown stain

[iamhives]

Just opened pool. 32k gallon in ground. Left it too long so it went slightly green, so shocked used Algaecide 60 and water clarifer. Algae cleared up OK. Water PH was low so started to raise it, hardness also low. Added baking soda (13lb) to increase alkalinity and PH a bit) and a bit more algaecide. Pool walls then got a uniform slight beige color. A vitamin C tablet makes it go white so I assume metals? Water is very slightly cloudy but the stain seems to be the immediate problem

Before I make matters worse, wanted to check here. Got the values below from a test kit to double check test sticks

PH 7.2
FC (either almost zero (test kit) or 3 depending on whether you believe the test kit or strip) I suspect too low
TA 50 - 60
TH 100
Calcium hardness 140
CYA 90

I use trichlor tablets and calcium hyperchlorite shock and sometime liquid chlorine (just bought more of the latter)

Suggestion?

 

[borjis]

Yep you have iron. Lookup AA treatment aka ascorbic acid. That will clear the brown.

 

[iamhives]

OK. Two steps forward, one step back. Used absorbic acid (3lb for 32k pool). Stain completely removed within about 2 hours. Water clear for a couple of days. Ph still around 7.2, TA about 80. Added a little agahecide 60 since clorine is near 0. If I understood AA process correctly need to only increase CL slowly. Problem now is that the water has become slightly cloudly (milky) but stain still gone. What now. Again, want to check before I make things worse. I have Jacks Pink stuff and Natural Chemistry Metal out and clarifier in the store cabinet (I think).