After hurricane Jimena we had between 26 and 50 inches of rain here in San Carlos, Sonora, Mexico. Because of this we had no electricity for about a week. We were gone and the person who maintained our pool that normally uses a SWG for chlorine threw 3 inch chlorine tablets into the bottom of the pool to prevent the pool water from going bad. Needless to say, this bleached the bottom of the pool which is plaster with Hidrazzo goulstrem blue. We now have 6 inch diameter spots that look like mold. The pool maintenance person has brushed them which did nothing. What is the best way to fix this? Do we need to completely drain the pool?