Day 3 update.
Brown stain appears to be getting a bit less bad. I have been running filter and S20 Pool Vac pretty much constantly, and doing 4-5 brushings a day. I do notice on the white grout below the water line is slightly less white that the grout above the water. Since the grout is only 4 months old, should not have changed color much. I am guess one of the reasons the stain is looking less bad is that the entire pool is getting slightly stained? But overall, if the stain continues to 'blend in', I will just live with it.
I have yet to try the Vitamin C test (thank
@kimkats for the idea). Plan to go out and buy some and try that today or tomorrow.
No other word from Morton. All they said they would do is to give me coupons for more salt, if I can find a store that will accept them as apparently Home Depot often does not. That, and they agreed to pick up the unused bags 'for free'. I could have returned them to Home Depot and actually gotten my money back, but I do not want to risk them putting that stuff on the shelf for someone else to buy. Home Depot would probably do just that. Aside from the headache and unknown future of my pool stain, I am also out $400 in expenses so far ($130 for salt, $70 for clarifier, $200 for 4 x 3030 pleated filters). Not going to break the bank, but not ideal.