So I've been battling metal stains with ascorbic acid, I've probably attempted it at least 3 times and the stains have returned each time. It's getting frustrating and expensive. Most recently I added ascorbic acid on Monday evening, circulated for an hour or so, stain was basically gone, I added 3 bottles of jack's blue stuff, then turned on the filter. Tuesday morning the stain was completely gone. Tuesday evening, I checked levels an I was at:
I decided to proceed slowly and using the pool calculator for my 30000 gallon vinyl pool, I figured I'd bring ph up with some baking soda, I figured I'd shoot low and try to bring it up to 7.0, so I added 48 oz of baking soda by volume dumping it in front of returns. I also figured I'd aim low on the FC, so I shot for FC 2, which was like 124 oz. We apparently had a pretty good storm overnight, when I woke up this morning it looked like the stain had returned on the liner. I checked FC and PH and as expected FC was at 0 and PH was somewhere between 6.8 and 7.0...
Any advice before I run off and get more ascorbic acid and sequestering agent? Like I said I've done this a few times, the first time I think I shocked too soon, the second time everything seemed ok and the stain was gone for like a month, then it returned and offhand I can't think of a reason, my PH was consistent around 7.2 the whole time, and I was holding my FC in my CYA range, this time I'm just plain baffled...