Hi my mom just bought a house in south florida, while looking through the house i noticed the pool had black/dark green spots all over the bottom, water was clear though. I have read that i need to test the water and that this will help you guys in helping me, but unfortunately i am not there right now but will be there starting tomorrow for a little more than a week. I started scrubing the algae with a s/s brush and it does come off, it took about 3 hrs but i got about 3/4 of the pool done, now i have to do the deep end. My question is it is leaving green little stains wherever i have scrubed, how can i get these out? I read that you can use a chlorine tab, but it would be the whole bottom of the pool. With what i saw yesterday the only background on the pool is it is 14,000 gallons, salt water system, conc/pebble bottom.