Meeting spa maintenance challenges
With all the factors working against the operator of a spa, what can the operator do to ensure an optimal user experience?
Maintaining sanitizer residual
First and foremost, sanitizer residual must be maintained within the recommended range for the chosen sanitizer, whether it is bromine or chlorine. Overall, bromine is less affected by increased pH, brominated compounds are less likely to leave the water due to volatization and bromamines are comparable to hypobromous acid as sanitizers. In order to provide a continuous bromine feed, install a properly sized brominator. Then, test the bromine residual and adjust the flow through the brominator to be sure the feed rate is well suited to the spa’s use pattern. Automatic controllers are helpful, so long as one understands their nuances, particularly when it comes to feeders.
Supplemental oxidation
Supplemental ozone oxidation is also strongly recommended, whether chlorine or bromine is the primary sanitizer. That said, some contend that with bromine-based systems, ozone is consumed, thereby regenerating the bromide ion back to hypobromous acid and negating the oxidizing support. This contention, however, is debatable.
Careful monitoring
In order to maintain proper water balance, spas require close attention. Knowing that the tendency of the spa water is for alkalinity (AT) to decrease while pH increases, operators must rebalance the water frequently to the upper range for alkalinity and lower range for pH.
Buffering systems
Another potential spa chemistry remedy is the use of a phosphate (PO43-)-based buffering system, in addition to a carbonate system. The phosphate system is not subject to the same loss of a component due to volatilization as the carbonate system. However, be sure to check local regulations relative to governing the amount of phosphate permissible for discharge.
Adjusting operations
Operational activities can also improve the ability to maintain proper water balance. These include not operating the aeration feature unless bathers are present and covering the spa when it is not in use. Also, when applying water balance products, operate the circulation pump at the lowest speed and do not use aeration.
Scale inhibitors
Use of scale inhibitors is also recommended to help control calcium carbonate deposits.
Follow draining and refilling requirements
In commercial spas, if the water volume is greater than 4,000 L (1,056 gal), Ontario regulations require make-up water to be added daily based on the number of users (30 L [8 gal] per bather use, to a maximum of 20 per cent of the total spa volume). For spas less than 4,000 L, the following equation below is used to determine how many days may elapse between draining and refilling:
WRI = V/(10 x U)
- WRI = maximum number of operating days that may elapse between drainings
- V = total volume of the spa in litres
- U = total estimated number of bather uses per operating day
While these guidelines are for commercial spas, they can also have a positive impact on residential units.
Finally, a spa filter is an environment that encourages bacterial growth. As such, they should be cleaned each time the spa is drained and refilled, using a specially designed filter-cleaning product. Larger spas that require daily water additions should use the equation for refill frequency on smaller spas as a guideline for frequency of filter cleaning.
Mary Costanzo is manager, technical service and process excellence, technology, with BioLab Inc., a Chemtura Company. She has more than 22 years of experience in technical support for pools and spas and has experience in new product development and prelaunch field testing, as well as technical training, quality assurance and process excellence. She is also a Certified Pool Operator (CPO) through the National Swimming Pool Foundation (NSPF) and an active member of the National Sanitation Foundation (NSF) Standard 50 Joint Committee.
