Prefilter 6473-364 SpaGuardTRIO This was used on hot

This was used on hot tubs with the LCD control system only

This non-chlorine shock is the ideal oxidizer for spas as it makes undesirable compounds disappear

then this is likely the culprit

of this product for each 500 gallons of water

Prefilter 6473-364 SpaGuardTRIO This was used on hotJacuzzi 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.