Frequency – These tests should be carried out on a monthly basis, or when the spa is first used or recommissioned, after a report of ill-health, if there are problems of contamination, or if there have been alterations in the treatment/maintenance programmes.
If there are reports of ill-health from bathers further testing may also be required for other organisms including Staphylococcus aureus, Cryptosporidium, Giardia and possibly viruses.
Monitoring pool balance and pH
In addition to routine microbial analysis of pool waters regular chemical testing should also be carried out.
One of the most important chemical parameters you’ll need to keep under control in your swimming pool or spa is the pH of the water, often referred to as the “balance”.
This is a way of determining how acidic or alkaline the water is.
Adding pool chemicals to the water can often change the pH levels and may prevent other chemicals from working as well as intended.
pH is measured on a scale of 0 to 14. 0 is an extremely strong acid, 14 is strongly alkaline, and at the mid-point, 7, the water is neutral.
Experts agree that the ideal pH range for water in swimming pools or hot tubs is between 7.2 and 7.6.
This is a range which is comfortable for skin and eyes, allows chlorine added to the water to work properly, and within this range water scale problems are unlikely.
If the water pH starts to fall too low into the “acidic” range, you may find that the water becomes irritating to skin or eyes, pool equipment including heater elements start to corrode.
You may also start to notice a build-up of minerals around the edges of the pool itself.
On the other hand, if the water becomes too alkaline, you might notice skin irritation, but also water clarity reduces and scale starts to form on the sides of the spa or pool.
In the UK, mains water from the tap will have different pH levels depending on where you are in the country, how your water is treated and local geology – what type of rocks the water flows through on its way to your local reservoir.
It’s therefore impossible to set-out a standard water treatment regime which works for everyone, as the water in tubs will tend to be different from the start.
Monitoring chlorine levels in your swimming pool
Measuring levels of chlorine or your biocide of choice in pool water is also important.
Chlorine is currently the most popular biocide for the control of bacteria in pools but needs to be maintained at optimum levels – enough to kill any bacteria in the water, but not too much to cause health issues for bathers or accelerated corrosion of the equipment and other components used in the pool or spa.
Testing chemical parameters
There are various ways of testing the essential chemical parameters in your pool water including pH and chlorine (usually free or total chlorine).