The key parameters for balancing a spa are pH, total alkalinity, and calcium hardness. pH should be between 7.4-7.6 and can be adjusted with pH increaser or decreaser. Total alkalinity needs to be monitored and maintained between 125-150ppm due to water movement and temperature causing it to decrease. Calcium hardness should be 100-200ppm and can be increased with calcium hardness increaser. Maintaining proper balances through testing and adjusting these parameters is important for equipment protection and bather safety and comfort.

1. BIO210: SPA BALANCING
Pool & Spa University
Image © Sykes Cottage (www.sykescottages.co.uk)

2. BALANCING A SPA
➤ The balancing parameters of a spa are very similar to the
parameters of a pool.
➤ The primary parameters in a spa:
➤ pH
➤ Total alkalinity
➤ Calcium hardness
➤ Generally, you do not test for cyanuric acid in a spa, as the regular
requirement to drain and refill combined with a spa cover
reducing evaporation prevents the need for maintaining stabilizer.
➤ You do not test for algicide in a spa; the rapid water movement
and higher sanitizer levels in a spa generally prevent algae growth.

3. RECOMMENDED RANGES
Chlorine Bromine
Soft Soak®
(Biguanide)
Soft Soak®
TRIO™
pH 7.4-7.6 7.4-7.6 7.4-7.8 7.2-7.6
Total Alkalinity 125-150ppm 125-150ppm 80-120ppm 100-120ppm
Calcium
Hardness
100-200ppm 100-200ppm 200-300ppm 150-200ppm

4. PH
➤ As discussed in the Water
Balance course, pH is the ratio
of hydroxide (OH-) ions and
hydrogen (H+) ions. As the
concentration of hydroxide
ions increases, so does pH.
➤ For spas, there is both pH
Increaser and pH Decreaser.
➤ These are the same
chemicals as Balance Pak®
200 and Lo ’n Slo®.

5. TOTAL ALKALINITY
➤ As discussed in the Water
Balance course, alkalinity is
composed of a series of buffering
agents, one of which is
bicarbonate.
➤ Thanks to rapid water
movement, increased
temperatures, and aeration,
bicarbonate will be forced out of
the water; this will cause the
total alkalinity to drop over time.
➤ Use Total Alkalinity Increaser
(the same chemical as Balance
Pak® 100) to increase total
alkalinity.

6. CALCIUM & SCALE
➤ As discussed in the Water
Balance course, a proper calcium
hardness level is needed to
protect equipment and surfaces
while minimizing the risk of
scale.
➤ In areas with soft source water,
use Calcium Hardness Increaser
(similar to Balance Pak® 300) to
raise calcium hardness to the
recommended minimum.
➤ In areas with hard source water
or metals in source water, use
Stain & Scale Control to reduce
the risk of scale formation.

7. SPA SENTRY™
➤ One option for maintaining spa
balancing is Spa Sentry™, a
phosphate-based buffering agent
designed to control pH.
➤ Some balancing of total alkalinity
may be required when first applying
Spa Sentry™.
➤ Spa Sentry™ is designed to last
between 30 and 60 days; the length
of time between product applications
is dependent upon the sanitizer of
choice.
➤ Spa Sentry™ will be consumed
faster in systems using more low-
pH products, like Brominating
Tablets.

8. CONGRATULATIONS!
You have completed the activity!