Possible brush damage to pebble finish

[jbakos]

Hello everyone,

I have a 3-year old pool with a WetEdge finish (similar to Pebble Tec). A few weeks ago, our neighbor was working on his roof and dropped some roofing nails in the pool which quickly caused rust stains. After failing to get results with vitamin-C tablets, I foolishly followed some really bad advise on YouTube that instructed me to use dry acid in a sock and a 6" stainless steel algae brush. This did eliminate the stains but it also discolored the finish. It made the larger black pebbles reflective, it somehow changed the grain pattern in the smaller pebbles, and it lightened the blue color. It isn't terribly visible unless you know where to look, but it's bothering me.

At first I blamed the acid--maybe it "burned" the plaster. But after some thought this didn't make sense because "reverse staining" from acid should only happen in older pools that have darkened finishes. Then I thought maybe the sulfates from the dry acid formed white crystals that attached to the plaster and caused the discoloration. To test this hypothesis I brushed the area with my nylon brush, and when that didn't do anything I gave it a few brushes with my stainless brush. At this point I immediately realized that it was the stainless brush--not the acid--that caused the discoloration. After this, I did a few Google searches and discovered that you're not supposed to use a steel brush on pebble. I'm guessing the brush must have discolored the plaster by scratching it, and the damage is probably irreverable..

Just in case, I thought I'd ask here if there's anything I can do to fix this short of replastering.