I have a new (built Oct 2015) pool at my new house which is on lakefront property. Until a week ago, the water and chemicals have been in good shape. I brush the pool almost every day because we don't have grass growing around the pool yet so it stays very sandy/dirty from the windy conditions and the deluge of rain we've had recently in East Texas. Over the weekend, I noticed some stains on the pool -- mostly from midway to the deep end. They look greenish and some are dark to me from above and from within the pool (looking through goggles). I couldn't get down to scrape any of it, but it didn't feel any different than the rest of the pool's surface when I ran my foot across one of the stains. Prior to my noticing this, about 3 weeks ago we had grass seed hydromulched, and a few days before I noticed the spots, we had a torrential 5 inches of rain and lots of dirt, grass seed, and who knows what else washed into the pool.
On Sunday, I checked all of my levels (FC = 4, CC = 0, PH: 7.4, CYA=70, TA=80, CH=300) and started SLAMing the pool. Finally, this morning, I had lost only 1ppm chlorine. The CC has been 0 this entire time. The pool did look cloudy earlier in the week, but has cleared up and looked pretty sparkly yesterday. However, the stains are still there. I've brushed at least twice a day every day this week. Should I keep SLAMing or move on to something else to determine what these spots/stains are? What else should I be doing/looking for/testing for? I left a message with my pool builder to see if he could come out and give his opinion.
Thank you for your help!