Regardless of the sanitation regimen you use with your spa, you should test your spa water, and make necessary adjustments, no less than once a week. This is an absolute. Some may claim this is not necessary. It is!
There are various methods to test spa water, including test strips, titration, and specialized equipment. The most commonly used, as they are quick, simple, and inexpensive, are colored test strips that generally measure these 4 chemicals, though some will also measure for Free Chlorine and Cyanuric Acid (CYA).
- Total Chlorine / Bromine
- pH
- Total Alkalinity
- Calcium (Total Hardness)
These test strips should be inserted several inches below the water line and then read immediately as the colors will start to change within seconds. Notably, the pH test will change most quickly so its a good idea to check it first.
Titration is also a common method particularly for those who are also testing their pools. This involves the use of reagent drops (generally 5) and usually measures only Total Chlorine / Total Bromine and pH. The advantage to titration is its quite accurate and colors do not change quickly.
Several types of testing equipment are available that are highly accurate, but generally start at $100, so most spa owners stick with colored test strips.
Notes:
1) When testing pH be sure to wait 4 hours or so after adding pH Up or pH Down before testing for pH again. Testing sooner will result in an inaccurate reading.