The ultimate solution for any hot tub water problem
Despite well-meaning attempts to properly sanitize, oxidize, balance, and filter hot tub water, at some point (because of the combination of smaller volumes and larger bather loads) the hot tub will need to be drained and refilled with fresh water.
In the ’90s, a formula was developed to determine how often hot tubs should be drained and refilled with fresh water. This formula is a guideline for draining residential and commercial/public hot tubs. The first step is to convert litres to gallons by multiplying by 0.26. Next, take one-third of the total gallons of water in the hot tub and divide it by the maximum number of daily bathers (‘bather’ equals one 20-minute soak) to get the number of days between complete draining/refilling:
# of days = 1/3 volume (gallons) maximum # daily bathers
Scenario #1
- A residential customer has a 2,271-litre hot tub (= 600 gal).
- 600 ÷ 3 = 200
- Every day, two people use this hot tub (200 ÷ 2 = 100).
- Therefore, the hot tub should be drained and refilled every 100 days.
Scenario #2
- A commercial customer (e.g. health club) has a 5678-litre hot tub (= 1500 gal).
- 1500 ÷ 3 = 500
- Every day, 100 patrons use this hot tub (500 ÷ 100 = 5).
- Therefore, the hot tub should be drained and refilled every five days.
Spa water sanitation/oxidation
When selecting which sanitizing/oxidizing method to use for a hot water environment, there are a few basics that should be understood to provide the customer with the best value.
- Hot water environments deplete chlorine (stabilized or unstabilized) faster than bromine.
- Chemical reactions occur faster in hot water environments than in cooler water environments.
- Treatment chemicals are added in hot tubs in significantly smaller amounts than in pools.
- The ultimate solution to any pool/hot tub chemistry problem is fresh water.
- Organic loads are more concentrated in smaller volume hot tubs; each bather contributes anywhere between 10 and 100 million bacteria to the water.
With the basics out of the way, the most popular options available for sanitizing/oxidizing hot tubs can be discussed.
