I just got my pool built a little less than a year ago and I noticed a few weeks ago this green stuff growing all over the pebble. The pool man added a bunch of chlorine a week ago but not change. Pool man isn’t sure what it is either. I’m worried maybe it’s a metal of some kind oxidizing in the pebble? I did see it growing on the grout too. Hard to see in pictures but if you zoom you can see it. Anyone have ideas of what this could be and how to cure? Thank you!!! 
JamesW has you started. I'd also ask what test kit (if any) are you using? Hopefully not free store tests or strips. We recommend either a TF-100 (link below) or Taylor K-2006C for best most reliable results. Also tell us how you normally chlorinate the water. That tells us a lot. Finally, please update your signature with all of your pool and equipment info - much like mine before. We'll refer to it at each post. Thanks!
