Actually DON'T think it's algae but..

[Luric]

We have what appears to be yellow dust ont he bottom of some spots of our pool. We don't notice it until we brush - sometimes it look slike just dust and sometimes it definitely has a yellow tone. We passed the ONCL test twice in a row (last one was 16 drops at sundown, 15 at sun up, but that was during the 3 days it took to receive our replacement Dolphin, and there were a ton of leaves sitting on the bottom which I believe accounts for the .5 FC loss). Currently levels below. Am I missing something? Does it sound like maybe it IS algae and I need to SLAM for mustard? Again, I don't see the yellow unless I brush certain areas on the floor, never the walls, at times in the crease of the steps. It's hard to tell from my avatar, but we are surrounded by tons of landscaping.

FC: 7.5
CC: 0
pH: 7.5
TA: 80
CH: 300
CYA: 60 (I am planning to bump this up once I"m confident I don't need to SLAM)

 

[HermanTX]

Your FC level looks great, especially since you have a SWCG. The PM logs do not have much history. Have you been keeping your FC above 4ppm (per FC/CYA Levels) the whole time? That would give cause for concern if you let it decline in avertedly.
It is not exactly pollen season but since you have a lot of foliage around your pool - could something be dropping in causing the light film on bottom?

I would keep my FC up around 10 ppm for several days to see if it clears and also since you have your robot that will help.

 

[duraleigh]

If you pass the OCLT, you should be able to vac it into your filter and it will stay gone. If it reappears after you vac, then you have algae, regardless of your OCLT result.