Big fan of this site and the TFP method - 4 years!
Pool is open - there is something on the walls (30k gunite) that looks like a shadow - a little darker than surrounding areas.
It seems to brush off easily (well, brushing isn't really easy is it?) then looks like silt drifting in the water but the robo vac does not remove it.
Waiting to see if it comes back.
Can't really get a good pic.
Is it dirt? Silt? Algae?
Does anybody know of vacuum-powered/rotating/oscillating scrub brush that would make it easier to scrub the walls on a regular basis?