Hello from a long timer lurker here at TFP.
In Jan 2012, I bought a pool that happened to come with a house and a small slice of property. Dispite my utter neglect those first 6 months, I'm happy to say that I never let it turn green and we've become pretty good pals since then; especially after I automated the bleach additions.
I'm fairly certain I have mustard algae -- large, blotched areas that have a yellowish-brown haze, predominately on the south wall (i.e. shaded). It fairly easily brushes off into a cloud, but, my polaris sweeper does NOT pick it up (i.e. not dust/pollen). My only uncertainty is that it takes about 1-2 weeks to come back again. Is mustard algae that slow growing, or am chasing something else?
My plaster is very old and has flaked in a few spots. The edges of the flaked plaster tend to harbor black algae, for which I'm on a brushing routine to keep that at bay.
Water is sparkly clear. My chlorine consumption is low and stable. OCLT is <0.5 ppm. Full chemistry is here.
Assuming I do have mustard algae, I'm looking to add borate after I get my TA down to ~60-70. After that, do yet another mustard level SLAM and this time actually remove the light form the niche