Chalky powder on pool floor/stairs after AA treatment

[TigerGalLE]

So I followed all the rules doing the AA treatment for some metal staining. 24 hrs after adding the metal out my pool became very cloudy. This seems normal but my pool also has chalky residue on the bottom/stairs. I vacuumed it up this morning and then backwashed my sand filter and now at the end of the day the chalky residue is back. It looks like baking soda. What Is going on? I’ve had my pump running continuously. I’ve been brushing to try to stir it up to get it to filter. Is everything ok?
My pH is 7.2
FC 4 (have added about 96oz chlorine total and it does keep trending down. Will do an overnight test)
CYA 45
Salt 2800
TA 70

 

[ajw22]

Could be algae based on your FC comment.

BTW, your CYA is 50. We always round up.

 

[TigerGalLE]

My chlorine held over night. White chalky powder remains. I’ll brush today and hope it filters.