2. POOLS V. SPAS
➤ As previously mentioned, there are some outstanding
differences between pools and spas that make routine care a
little different. While we briefly touched on them before, we’ll
go into more detail now, including both how they are different
and why this difference matters.
➤ The primary differences in a spa versus a pool:
➤ Water temperature
➤ Turnover rate
➤ Aeration
➤ Bather effects on water
3. WATER TEMPERATURE
➤ The water temperature in a pool typically measures between
78 and 86°F. In a spa, the average water temperature is
between 98 and 104°F.
➤ Higher water temperature has an effect on the following
parameters:
➤ Sanitizer volatility
➤ Carbon dioxide volatility
➤ Calcium solubility
➤ Rate of bacterial growth
4. WATER TEMPERATURE
➤ Higher water temperatures in a spa mean that sanitizer of all types will leave the
water faster than in a pool.
➤ Bromine will remain longer than chlorine due to the weight of the compound;
bromine atomically is heavier than chlorine.
➤ This ultimately means that you will use more sanitizer in a spa to maintain a
proper residual.
➤ Higher water temperature will also promote the breakdown of bicarbonate buffer
(HCO3
-
) into two byproducts: hydroxide ions (OH
-
) and carbon dioxide (CO2).
The carbon dioxide is then released as a gas.
➤ The problems here are twofold: the breakdown of bicarbonate results in a
lower alkalinity and the increase of hydroxide ions results in a higher pH.
➤ Higher water temperature also makes it harder for the water to keep calcium in
solution, meaning that water clarity concerns and scale are more likely to happen.
➤ Finally, higher water temperatures promote accelerated growth of bacteria.
5. TURNOVER & AERATION
➤ The turnover rate in a spa is much faster than a pool:
➤ Average turnover rate for a pool: 6 hours
➤ Average turnover rate for a spa: 30 minutes
➤ This rapid movement of water will promote removal of carbon
dioxide from the water, same as outlined in the previous slides,
resulting in higher pH and lower alkalinity.
➤ Spas also have aeration, or the forced introduction of air into flowing
water. This air is part of what gives jets their power, but aeration, like
rapid circulation, forces carbon dioxide out of the water.
➤ Aeration can also force sanitizer out of the water, increasing the
need for sanitizer applications.
6. BATHERS’ EFFECTS ON SPA WATER
➤ One person in a spa is very different from one person in a pool. In general,
there will always be less water per person in a spa versus a pool.
➤ e.g. 2 people in a 350gal spa is equivalent to 200 people in a 35,000gal
pool.
➤ e.g. In a 35,000gal pool, 4 people have 8,750gal each, while 4 people in a
350gal pool have 87.5gal each
➤ As a result, bathers have a much larger outsize effect on water chemistry and
care in a spa than in a pool.
➤ The higher water temperatures and rapidly moving water also promote an
increase of contaminants from human bodies:
➤ Increase in perspiration (sweat)
➤ Rapid removal of dead skin cells
➤ Rapid removal of body oils
7. BACTERIAL GROWTH
➤ All of these factors—higher water temperatures, rapid water
movement, aeration, and reduced relative volume of water per
bather—all promote disease transmission.
➤ Waterborne illnesses can range from relatively mild, like contact
dermatitis, to potentially fatal, like Legionnaires’ disease.
➤ Preventing disease in a spa is a #1 priority that can be
accomplished through proper sanitation, oxidation, balancing,
and taking into consideration the four differences mentioned
previously.
➤ In all circumstances, if a customer indicates they have
become ill after using their spa, advise them to see their
physician. You are not a doctor and cannot diagnose illness.
