What to Know About Water and Your Pool Service or Spa Care

Maintaining the Water Chemistry for Your Pool and Spa

While it’s been stated that maintaining your water chemistry isn’t rocket science, it does require knowledge about the science of water and how to keep it in balance.   Regular pool service or spa maintenance will ensure that the water in your pool or spa is balanced and sanitized and therefore safe and ready to use when you want to.

Balancing the water in your pool or spa means maintaining its pH level so it is neither Alkaline (Basic) or Acidic.  What is the pH level you ask? Well it is a relative measurement of a sample of water’s characteristic acidity or alkalinity when compared to pure water.  The pH scale goes from 0 to 14, and pure water has a pH of 7 (right in the middle).

Here is a graphical representation of the pH scale:

The water in your pool or spa should have a pH between 7.2 to 7.8.  When it is outside this range the water can cause damage to your equipment, cause scaling or pitting on the pool’s interior, and even be harmful to swim in.  By employing the services of a professional pool service or spa maintenance company you can avoid the consequences of out of balance water and leave the worry and hassle to them.

Professional pool and spa service technicians utilize a variety of methods to ensure your pool or spa’s water remains in balance. During weekly pool service or spa maintenance calls one of the first things they will do is use a professional grade test kit to determine what the pool or spa’s current pH level is.  Water chemistry test strips are also an available method for testing pH, but their accuracy does not match that of a professional pool service or spa maintenance test kit.

Balancing the pH for Pool Service and Spa Maintenance

Once the pool or spa water’s pH is determined, then your technician may add one or two compounds to the water to keep its pH in the desired range of 7.2 to 7.8.  If the pH is determined to be high (or basic) then the technician will add Muriatic acid to increase the acidity of the water and therefore bring down the water’s pH level.  The pH of Muriatic Acid is less than 1. So adding it to water that is determined to have a high pH during a pool service or spa maintenance call will help balance the water’s pH bringing it down to the desired range.  How much acid is added is determined by many factors including pool or spa volume. Your professional pool or spa technician will understand what is needed to keep the pH balanced.

Conversely, if the pH of your pool or spa is determined to be low (acidic) then your technician will add a basic or alkaline compound to the water to bring the pH up.  The most common ways to increase the pH of pool water is by adding Soda Ash or Sodium Bicarbonate. These compounds have pH levels in the basic range.  Soda Ash’s pH is over 11. So adding it to pool water will increase the pH quickly. Sodium Bicarbonate has a pH of 8.3 to 8.6. So it will raise the pH more slowly. Again, your professional technician will understand pool and spa chemistry and add just the right amount of either of these compounds during your weekly pool service or spa maintenance visit.

Pool Service and Spa Maintenance and Total Alkalinity

Another important factor when considering your pool or spa’s pH is it’s Total Alkalinity.  What is Total Alkalinity you ask? Well Total Alkalinity is a measurement of the concentration of alkaline substances dissolved in the water.  So why is this important? Well the alkaline substances dissolved in the water neutralize the acids in the water and therefore act as a buffer for maintaining the pH.


The desired range for Total Alkalinity is 80 to 100 parts per million, and your professional pool service or spa maintenance technician will understand how to achieve this.  Maintaining the proper Total Alkalinity of your pool or spa water will prevent what is known as pH bounce where rapid swings in the pH occur and the water is not balanced.

Chlorine or Bromine for Pool Service and Spa Maintenance?

The next thing to consider when understanding pool or spa water chemistry is sanitizer.  Other factors like pH and Total Alkalinity can be perfectly balanced, but if there is no sanitizer in your pool or spa water then bacteria and other harmful organisms can form.  The most common forms of sanitizer for pool and spa water are chlorine (in several forms) and bromine.

Bromine and chlorine are very similar in the way they kill bacteria and other harmful organisms, but these two compounds react differently in water depending on the temperature.  For spa maintenance your professional spa technician will most likely recommend bromine for the sanitizer because it is more stable than chlorine at higher temperatures. For pool service, your professional technician will recommend chlorine because it is much cheaper to use, and the volume of most pools makes using bromine for their sanitizer to be cost prohibitive.

pool service

For pools and spas the ideal level of sanitizer is 1 to 3 parts per million, but this can sometimes be hard to consistently maintain between weekly pool service or spa maintenance visits, especially during the summer.  To sanitize the pool or spa water, chlorine and bromine combine with the bacteria or harmful organism to kill it. Once this combination occurs the chlorine is reduced and the waste product is removed from the pool or spa by the filter.  With bromine more of the compound is left behind after it kills the harmful organism resulting is the bromine level remaining more consistent as compared to chlorine.

Another factor that causes the chlorine level to go down in a pool is the UV radiation from the sun.  The total chlorine level in your pool is determined by the amount of free chlorine and combined chlorine.  Free chlorine is just what is says. It’s freely available to attach to harmful organisms and kill them while combined chlorine has already done its job.  Available free chlorine in your pool can be quickly reduced by UV radiation by having the molecules broken apart making it useless.

To counteract the destruction of free chlorine by UV radiation,  your pool service professional will add conditioner, also known as Cyanuric Acid (CYA) and stabilizer.  The conditioner binds to the free chlorine molecules in your pool preventing the UV rays from breaking them apart thereby “stabilizing” the amount of free chlorine in your pool available to kill harmful organisms.

In summary a professional pool service or spa maintenance technician will be an expert in pool chemistry and understand how best to keep your pool or spa water balanced and sanitized to ensure it is looking good and safe to use at all times.