Spas & Hot Tubs

Spa Chemistry

An important aspect of maintaining a spa is proper water chemistry. The sanitizer level must be in the desired range at all times, and the pH and Alkalinity must be kept in check. There are many different spa-sanitizing chemicals on the market today, and regardless of the type of sanitizer you choose to use, you must sanitize continuously. Harmful bacteria can grow very quickly in the warm environment if the spa is poorly maintained. The most common sanitizer used in spas is called Bromine. Bromine is a chemical very similar to chlorine in the way that the chemical kills bacteria to sanitize the spa water, however bromine is much softer on the skin and eyes of bathers. Click here to shop for quality spa chemicals at competitive prices.

In addition to testing and maintaining the sanitizer level, a spa must also be “shocked” on a regular basis or after each use. When the bromine in spa water combines with bacteria and other organics the bacteria is dead and harmless. Although the bacteria is dead, it is still present in the spa and must be removed. Shocking the spa burns off all of the dead bacteria, and frees up some of the bromine cells to kill bacteria again.  To help you understand the importance of shocking the spa, the National Pool and Spa Institute (NSPI) has determined that the bather waste created by four people in a spa is equivalent to the amount of bather waste created by 160 people in a standard backyard pool. 

Other important chemical levels that must be tested and adjusted regularly are the pH and Alkalinity levels. The pH is the measure of the acidity of spa water, and should be maintained at 7.4 - 7.6 ppm (parts per million). You will typically find the pH level of spa water to be higher from one test to the next because the high water temperatures and the aeration of the spa jets naturally increase pH. The Alkalinity of the spa water acts as a buffer to prevent the pH level from fluctuating, and should be maintained between 100-120 ppm (when using bromine as a sanitizer). If the Alkalinity is properly maintained, the pH level is much more stable and adjustments are required less frequently.

A residential spa must be drained by the homeowner at least every 2-3 months, or more frequently under heavy use.  The NSPI has created a convenient formula to help you determine how often you should drain your spa. To use this formula you need to know the volume of water the spa holds (in gallons) and the average daily bather load. The formula is the spa volume divided by three, and divide the result by the average daily bather load. The final result is the number of days you can go between each draining. In many commercial spas, this formula indicates that the spa needs to be drained every day!  After a spa is drained and re-filled with fresh water all of the chemical levels must be tested and adjusted accordingly.

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