Hi, need some assistance with this stain. I live in Fl and have a 22,000 gal. pebble-tech sand finish pool. Previous owner of the house had installed gutters but didn't drain the water away from the pool so when there was as storm the pool filed up and overflowed the paver coping. As a result I have this nice stain around half my pool. I have tried chlorine and acid, (scrubbing with a stiff nylon brush) no change. Any suggestions wold be greatly appreciated.
Thanks in advance.