Our pool has Wet Edge Satin Matrix in the Northshore Carribbean color. The pebble contains a moderate amount of black pebbles as well as tan and blue. I have seen smooth white plaster pools with algae before, but never a pebble pool. Isn't if very difficult to see the algae with so many pebble colors? I am concerned as my FC fell to around 1.5 today when I tested and then after running the Polaris 9300 robot I had streaks on the walls where you could easily see where he had scrubbed. Looked like the plaster was brighter blue where the robot had cleaned. I then went around the pool with the nylon brush and brushed the sides. However, even by brushing very hard I could not make the plaster bright like the robot did (in the dull areas). I have heard that the walls may feel slimy if algae is present. The walls are not slimy feeling at all. Also the CC is 0. If algae were present wouldn't you expect to see CC higher than 0?
I just want to know exactly what to look for just in case the culprit was to appear now or in the future.
On another topic my robot still pulls out small pebbles when cleaning. Not near as many as in the first couple of months after pool build. The pool was finished & opened in August of last year, (9 months old). Is this normal?? I emptied about 1/2 teaspoon of pebbles out of the robot filter today. CH = 270