Guys, with moving in to a new home with salt water pool I had a couple issues early on where my calcium levels were low and I had next to nothing of Chlorine, since fixing the issue my chlorine was a bit high at about 5 for a while untill I lowed my SWG enough so it started dropping, I think its about 3 right now. What I did notice just today, though, while adding muriatic acid to lower PH that my light covers had a greenish looking substance on it. I am still new to pools and ofcourse first thing came to my mind is algae, but chlorine is high enough, the pool water looks crystal clear. The substance come right off the covers, I dont even have to wipe it, its enough that I run my hand across the water in the area of the lamp and the stuff comes right off the glass. Does anyone have any idea if it just some kind of dirt or is it some other problem? It does look greenish while looking from above but cant really tell for sure.