Discoloration in Buff lueder stone

[shelley12]

Hi, we installed our pool a few months ago and have noticed discoloration in the lueders around the pool. The pool company says it might be our chemicals but we have had them tested and everything is great. The designer says she’s never seen this before. Any suggestions?
thank you

 

[Texas Splash]

Welcome to TFP! Might help to have @jimmythegreek take a look at these images.

 

[jimmythegreek]

What is the coping material? Was it all sealed after install? How are you sanitizing the pool do you use chlorine or a SWG