Backstory: I'm military and was deployed from Jan-May. During that time, we had a cover over the pool that loosened over time, allowing a lot of leaves, dirt, and other debris in the pool. When I got home, I removed the cover and saw all the debris on the bottom. I started the SLAM process at the same time I had the vacuum going to remove all the stuff off of the bottom (I think this may have been a mistake, probably should have vacuumed first). On day two of the SLAM, the water cleared up pretty well and I noticed stains on the bottom of the pool. No big deal I thought, there was still a lot of dirt on the bottom and I'm sure it'd clean up. After the SLAM was complete, the stains still remained. No type of brush, vacuum, or even pressure washer could remove them.
Fast forward 2 months now, and the stains still remain and have gotten worse throughout the entire pool. I decided to do another SLAM to see if perhaps there was some lingering algae that I never got rid of throughout the summer. The SLAM didn't help. Below are my pool stats. I know my CSI is extremely high right now, but I think that is due to the SLAM (specifically the pH). The zero CYA is killing my chlorine levels, but I have some in the pool as we speak.
In the pic, you will see tracks made by my vacuum. These tracks were made on day 2 of my initial SLAM and have not disappeared. So that tells me is that me adding chlorine to the pool made some reaction with the debris to stain the surface. In other words, no staining took place until I started the SLAM.