I know this is an older thread, however, I had the same Pentair rust issue and hopefully have added another step to prevent future issues. I ordered a new stainless ring. When I received it, I cleaned/prepped the spot welds and area around it (rust begins here). I then coated the area with POR 15 and let cure for 96 hrs. I happened to have some Gray POR15 from a previous project.
I removed the rusty stainless ring in the filter and cleaned the rust on the inside of the housing with Barkeepers Friend. Finally I reassembled everything and started the system back up. I'm not 100% sure this will prevent future rust, but I feel a lot better with it coated in POR 15, than without. Fingers crossed.
I removed the rusty stainless ring in the filter and cleaned the rust on the inside of the housing with Barkeepers Friend. Finally I reassembled everything and started the system back up. I'm not 100% sure this will prevent future rust, but I feel a lot better with it coated in POR 15, than without. Fingers crossed.
