New pool owner battling brownish spots on one of my benches. They just started showing up over the weekend when I accidentally ran the pool down to 0.15 ppm FC with water temps around 85 - 87. Water looked slightly cloudy and a little green. I shocked the pool that night, and everything from a water chemistry stand point is back to normal. The spots disappeared when I rubbed a chlorine tablet on them, so whatever it is its organic. But these spots keep popping back up almost daily on that bench (though not in the exact same spot) despite the shock. I continue to rub a tablet on them, and they disappear for 12 or so hours and start coming back. It lightens somewhat with aggressive scrubbing, but doesn't completely disappear.
I'm just not sure what it is I'm battling. Given the level of chlorine I added (2 gallons of liquid shock to take it to 20 ppm) I'm surprised anything organic is living. I don't have any metal in the water either, and in any case chlorine makes whatever it is disappear. For what it's worth - I'm in Central Texas and we're dealing with the mother of all pollen seasons, its dumping yellow pollen and dead live oak "flowers" all over the place.
I didn't think to take any pictures, but imagine dime to quarter size yellowish brown spots on the deep end bench (and only the deep end bench) that disappear when chlorine is directly applied.
Thoughts?
I'm just not sure what it is I'm battling. Given the level of chlorine I added (2 gallons of liquid shock to take it to 20 ppm) I'm surprised anything organic is living. I don't have any metal in the water either, and in any case chlorine makes whatever it is disappear. For what it's worth - I'm in Central Texas and we're dealing with the mother of all pollen seasons, its dumping yellow pollen and dead live oak "flowers" all over the place.
I didn't think to take any pictures, but imagine dime to quarter size yellowish brown spots on the deep end bench (and only the deep end bench) that disappear when chlorine is directly applied.
Thoughts?