I've been a TFP supporter for several years. I've come here in the past to read and learn about a recurring problem I have with metal (copper) stains. I understand the consensus here seems to be that if after stain removal and phosphonic based sequestrant, if the stains return, it means "you weren't using enough sequestrant".
Unfortunately, I'm adding about a quart of sequestrant a week and much to my dismay, the stains always return in the span of 7-10 days. My pool is only about 23k gallons.
I've decided to hire someone to completely replumb my equipment to # 1, replace all the cheap PVC valves with Jandy Neverlube valves and # 2, to add valves that will allow me to completely bypass/isolate my pool heater. I suspect that my copper issue must be coming from the heat exchanger. I am VERY diligent about keeping the chemistry as suggested here and use the TF-100 test kit. However, as the years progress, my metal stains only worsen from season to season. I wonder if I'm in a cycle where the metal stains appear, treating the pool for the stain removal lowers the pH which may be further corroding my heat exchanger. Since we only use the heater 2-3 times early in the season, I figured it can only help to drain and fully bypass the heater the rest of the season.
Unfortunately, I can't seem to add enough sequestrant to keep the stains away. This stain removal cycle every 7-10 days is REALLY expensive.
Here are some photos that illustrate how bad the staining can get and how quickly the metal removing chemicals get rid of the stain. As you can see, on Saturday evening, the liner stains are visible in the deep end. Sunday morning, it's a mess.. etc.
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