When we opened our fiberglass pool, we had about 3/4 of the pool surface covered with a stubborn stain that could not be brushed off. After trying a few things to figure out what kind of stain it was, it responded to some vitamin C tablets, so I figured it must be a metal stain. I poured in a container of Stain Free and 24 hours later nearly all the stain was gone. I brought chlorine back up (FC 2.5 with CC 0) and maintained the TA, CH, pH, and CYA at the levels I have used for the past couple of years.
The staining returned. Since this staining is new, it can be brushed off the sides and bottom of the pool. After brushing while the filter is running, the water becomes very cloudy. I thought the filter would pick up the brushed-off stain, and we would have clean water. But, just a few hours after brushing, you can see the stain returning. I dumped in a bottle of Jack's Magic Purple sequestrant. I did not see any change in the water.
I bought some AA, lowered the chlorine, and dumped in the same amount of AA as I had with the Stain Free. It has been a bit over 24 hours since putting in the AA, and there is no sign of the staining going away
The staining looks exactly the same as the original staining. I am totally puzzled as to why the Stain Free eliminated the stain, but the same amount of AA did not.
We have never had staining issues with this pool in the past. I am confused and frustrated.
At this point I am thinking of getting some more Stain Free since it worked the first time. And, then I guess follow up with maintenance doses of Jack's Magic Purple sequestrant.
Can someone help me before I do something rash like drain the pool.