Gray Stains on Pebble Fina
I have had my pool in since the beginning of May and we've had some problems with calcium deposits but nothing very serious. We have Pebble Fina Bella Blue and add Jack's Magic Purple Stuff(for metal deposits) every week along with PhosFree and we use ScaleTec once a month as maintenance. I keep my PH down around 7.5 and my alkalinity is usually just at 120 and as soon as it hits 130 is usually when my PH hits 7.8 and I then add Acid. I check my pool water almost every day to keep things in check. My Chlorine level is usually 2ppm. My CYA is 90 and my Hardness is 260. My pool always sparkles and looks gorgeous so I'm a little confused.
Here's my question...
We have noticed some medium gray circle shaped Stains around the bottom of our pool(approx. 12 as of yesterday). Not on the sides, just on the bottom. It won't come off. We don't know what these are. My husband thinks they may be bird poo stains, but we really don't get bird poop in our pool. We get stuff blowing into our pool and we get spiders and ants in our pool, but nothing major.
Has anyone had this problem? How can we figure out what these are and take care of them?
I don't want to call my PB if this is not something to worry about or if it is something we can take care of.
Thank You for any advice.