This 2 inch by 6 inch core provides excellent, chlorine-free water for natural spas and hot tubs. Place inside your sediment filter – no plumbing work required. Keep a clean spa without chemicals.  SpaCore Natural Water Filter

Put these where the water is circulating.

Copper-zinc media maintains a bacteriostatic environment in the filter and removes heavy metals and inorganics. Releases low residual levels of copper and zinc ions into the water to prevent algae and fungus growth. This controls scale and renders chemicals inert.  Place the SpaCore inside your sediment filter. For spas and hot tubs up to 400 gallons – lasts 4 or 5 months.

More info: spa and pool filters.

If as a result of heavy usage, you can, if you choose, mini-shock your spa with chlorine or other shocking agent. Take the filter out for 12 hours, then then insert to clear the water again.  The filter will remove the chemicals.