I am a first-season pool owner, but thanks to these forums, I've had a mostly trouble-free pool all season. I did have to apply the SLAM procedure back in July to knock out some algae that had gotten away from me, and it worked just as described.
However, I've been recently facing a grey substance, which at first I did not think was algae because of the color. However, I've been SLAMming my pool for about a week now, and this grey substance persists. I've been brushing and vacuuming, and maintaining a shock level FC.
FC 28 (I add chlorine every night to get it above 28, up to 32ppm)
My last two overnight FC loss tests were 1.5ppm, so is this really algae? Any suggestions?
Bottom right corner, and on slope (left side of photo)