Our pool is just over a year old and has been BBB for it's entirety. Over this winter (not closed) I started to notice that some of the pop ups for the in floor cleaning system, intakes and drains have developed a light coating of something brown. All of the parts are plastic and I was just thinking that they were discoloring from the sun. I tried to brush it off with out any luck. I dove down and wiped it with my finger and most of it would come off. With a washcloth it comes of pretty easily. It does leave a light staining. It's mostly the plastic parts that are in the deeper section of the pool. The shallow end and the spa do not have it.
My chlorine usage has been normal.
I added a picture and you can see where I rubbed it to get the brown off. (By the way I am saying that it's brown because that's what my wife has told me. I am red/green color blind and could not tell what color it is.)
If it's algae then I guess that I am looking at my first ever shocking process. Yay!