For the first year ever (out of 5 years in total), we are experiencing yellowing on all interior plastic skimmer areas from water level to skimmer bottom, on plastic water return (underwater), and beginning on the liner bottom closest to the return.
Any ideas - stains of some sort? - on plastic pieces when vinyl liner walls look perfect? How should I treat? Could this be rust/corrosion from heater coils or a chemical issue?
Things unchanged: 24' above ground with 24/7 D.E. filter and pump running,
froger with chlorine and mineral reservor, SeaKlear 90-day algae treatment, GLB PH UP used to try to keep ph ok since we have a Ray-Pak heater constantly in the loop.
Things changed: started using Leslie's fresh and clear shock weekly replacing GLB product,
switched from GLB Sequa-Sol to 6 oz of Natural Chemistry metal-free (for 13,500 gallons).
Our water has always been crystal clear with no discoloration. Chlorine never over 3 ppm for the season and ph never recorded below 6.5 ever. Always brought pool back into perfect specs within a two week period.
Thanks in advance.