Prefilter 6473-364 SpaGuardTRIO of this product for each

of this product for each 500 gallons of water

J-300 Series Flow Switch 6560-852

Not only does it help prevent pH flucuations but it also replaces the need for Stain & Scale control and prolongs the life of your hot tub by keeping your spa components free of contaminents

then this is likely the culprit

Prefilter 6473-364 SpaGuardTRIO of this product for eachJacuzzi Pre Filter Fill your spa with the most pristine water possible. Use one of these with on each fill up. The Microfiber Disposable PreFilter takes out calcium, rust, sediments, and other undesirable elements from your water before you fill your spa. Good for up to 3 fills, the MicroFiber Filter meets FDA and NSF standards. Attaches to a garden hose and great for people using well water.