Hi everyone. I have a pool that for years gave me no issues. 3 years ago I switched to salt. year 1 no issue, last year water started to get green/brown and could not get rid of it. pool guy said is metal in water. this year I had similar problems, not to the extend of last year but still not clear. dark stains in liner and steps. they suggested to test the water faucet to see if any metal was present. no metal there. I bought a metal collector tool that since i put in skimmer helped a bit. water looks decent but stains are still there. the only thing i can think of is the heater (its 5 years old). pool guy has no solution just says that in NJ he sees many pools with this issue. but water has no metal in it.....i really dont know what to do. replacing heat exchanger for a non copper one is expensive and maybe that is not the problem. any suggestions? thank you