Another way to sanitize pool water without using more chemicals

By Jeff Boynton

Today, industry professionals face a number of questions from clients on how they can use fewer chemicals (i.e. chlorine [Cl] and/or bromine [Br]) in their pool, what alternatives are available to reduce chemical odours in and around the water, and what options do they have in cases where children may have sensitive skin and develop rashes or hives in pools using traditional sanitizing methods?

For several years, pool professionals have offered salt chlorine generators which have met many of these needs, but pool professionals are now finding ultraviolet (UV) manufacturers have improved their product designs to work on residential pools to provide additional benefits. For instance, UV sanitizers do not add anything corrosive to the water and do not require additional pH balancing acids as these systems do not alter the water’s chemistry. This makes UV sanitizers an easy, effective option for pool owners looking to reduce their chemical usage with the added bonus of reducing chloramines, unwanted smells, and skin irritations.

Getting Started

Before pool professionals can start selling UV sanitizers, they need to understand their benefits and how to select the proper unit for specific aquatic applications. Not all units are the same.

It is the pool professional’s job to understand the environment in which the UV system will be installed to determine the best unit for the client’s pool. That said, it is important to match the unit size to the pool type (e.g. flow rates, commercial/residential, and indoor/outdoor) in conjunction with the pool’s bather loads.

By understanding these differences, pool professionals can easily determine which unit to recommend. The following explanations will further assist in determining what type of unit should be installed.

Low- versus medium-pressure UV systems

There are two types of UV lamps: low-pressure, high-output lamps, which emit UV rays at 254 nanometres (nm), and medium-pressure lamps that emit UV rays between 200 and 600 nm.

Low-pressure lamps are better suited for residential applications, while medium-pressure models are designed for large commercial installations. The differences between each lamp are cost, flow requirements, and the ability to destroy chloramines (NH₂Cl).

Medium-pressure lamps are commonly used in indoor pool applications as their large light spectral is more effective at reducing the health problems caused by nitrogen trichloride (i.e. chloramines), which have been linked to numerous pool closures due to poor indoor air quality (IAQ).

Pool professionals dealing with an indoor residential pool, where air quality can also be a particular concern, should consider a semi-commercial or commercial UV unit to ensure the client gets the water and air quality improvement they desire.

For outdoor residential pools, UV units must be selected based on the pool’s flow rate to ensure the system properly eradicates waterborne pathogens. When working with a semi-commercial application, e.g. a hotel, motel, or fitness facility with flow rates more than 416 litres per minute (lpm) (110 gallons per minute (gpm), a low pressure, high output UV system, or an amalgam unit designed to accommodate higher flow rates, should be considered.

Most UV system manufacturers provide tables, charts, and even mobile applications for pool professionals to determine which unit their client should purchase based on the aforementioned factors. It is important pool professionals consult manufacturer guidelines when recommending a UV system to a client.