Hot Tub and Spa Owner's Corner

Hardness Recommendations for Spas with Ozone

1995 - Present
As of November 2005, Olympic Hot Tub Company has altered our recommendations for the amount of Calcium Hardness you should add to your tub at startup. This is due to Hot Spring’s current recommendations and improvements made to materials. We are now recommending a hardness level of 150-200 ppm for all Hot Spring®, Tiger River® & Solana Spas® that use ozone/EverFresh and were made from 1995 on.

If you are on Seattle-Tacoma City water, use the following chart as your new startup amount of Calcium Hardness. All other water sources (island water, well water, etc) should be tested for hardness before determining your new Calcium Hardness startup amount. A hardness test kit can be purchased at any of our stores, or online at our E-Store.

Gallons in Your Tub	Scoops*
500-525	7.5
450	6.5
400-430	6
350-365	5.5
325-330	5
300-310	4.5
270-285	4
240-245	3.5
205-215	3
130	2

*Scoops of Calcium Hardness for Startup. A scoop is a 2 oz dry measure

You are also welcome to drop by any of our locations with a sample of your water to be tested by one of our staff. Questions or concerns? Call our Service Center at 1-800-431-2876 within western Washington.