OK, I guess I will be joining this thread. I have the dreaded brownish stain all over the fiberglass below the waterline. Did a partial drain today, mostly to get rid of HIGH CYA. Tried scotchbrite pads, even pressure washer. NO JOY !

Going to try the Stain Remover (ascorbic acid) from Leslie's. The lable says I must use with Metal Free to pevent re-occurance. Buying that brand because I don't want to wait for a shipment. I will add to pool after re-fill is complete, and post results of stain removal tomorrow.

Jeff