In most cases, the introduction of phosphates in traditionally treated spas, especially spas which are covered when not in use, will never be an issue. Phosphates are already “fully oxidized” in water and have no impact on the performance of common oxidizers typically introduced to water. Such oxidizers include chlorine (in any form) and oxidizing shocks, such as potassium monopersulfate (KMPS). However, when a spa is equipped with a generator, excess phosphates may interfere in the generator’s ability to reliably produce chlorine.
Previously mentioned was the use of phosphonic acid to control metals in spa water. These acids work well to rid metals from water, or at least reduce the visual impact of metals in water. However, use of these products will also introduce phosphate to water. Sometimes the use of these agents is necessary to solve harder problems, but the use of such chemistries should be avoided on a continuous basis.
Filtering out phosphate in water
Preventing the introduction of phosphate from the source water or with the use of metal agents would be an ideal scenario, however, options for filtering out the phosphate in the filling stage are limited. When filtration is not an option, phosphate reducing agents are the next best solution. When reducing phosphates in spa water, gradually reducing the levels in the water is perhaps the best method, as it would avoid making the water turbid. Alternatively, reducing phosphate levels too quickly can cause the water to turn cloudy. In either case, the resulting precipitate allows the filter to capture phosphate. As a result, removing the filter and rinsing it is critical to removing phosphate or else it never leaves the water.
Spa and pool water maintenance
As with pools, a common headache of using a chlorine generator in a spa is keeping the pH in the preferred parameters. The constant rise of the pH from the cell operating is accelerated by the aeration of water from simply using a facility’s jet pumps or bubbler system. Ultimately, testing and adjusting the spa water more often is the remedy, which is the opposite of what spa owners are looking for, and that is more maintenance. The introduction of borate to spa water will introduce a secondary buffer system, and the net result, for most, will reduce the frequency where the pH and the alkalinity will need to be adjusted.
