The long lasting cartridge for the Watkins Freshwater system is here

Lance Fitzsimmons aka "The Hot Tub Wizard"

July 31, 2026

It’s been at least 3 years since I received my first request for an alternative to the cartridge that Watkins has been using in their Freshwater salt systems. They don’t last very long, about 3 or 4 months and there is no expectation of a warranty. The Chinese sellers on Amazon and eBay wasted no time in replicating these. I can’t even tell them apart when comparing the OEM and aftermarket. Our challenge was to make a cartridge that we could warranty for 1 year.

We have 2 versions, 1 made for longevity and 1 made for producing more chlorine. I noticed on my 2025 Caldera that it was difficult maintaining a chlorine residual even when putting it in the high power mode.  Unlike the ACE system which runs on 12 VDC, the new system runs at 7.5VDC and 6VDC.

Today, I placed a prototype in the cartridge receptacle on my tub and it works. I had to drain and add fresh water as mine had gotten up to 2000. Because these are built to last, I had to get the salt down to 1500. Adjustments will be made to make it a little less sensitive..

Installing new replacement cartridge for the Freshwater® salt system.

A close-up view reveals the intricate design of a wet blender blade, highlighting its sharpness and function.

The Caldera Spas control panel displays maintenance information.

A Caldera Spas control panel indicates high status with instructions to check and adjust the salt level or replace the cartridge.

Close-up view of a fuel cap and hose assembly.

Monitoring spa settings with the Caldera Spas control panel.

A close-up view reveals the intricate design of new replacement cartridge

Close-up view of the OEM and replacement salt cartridge

Monitoring spa salt cartridge with the Caldera Spas control panel.