Return to Main Site

Understanding the Balancing of Spa Water


The factors that contribute to water balance are free chlorine, pH, Total Alkalinity, cyanuric acid, Total Dissolved Solids, calcium hardness, phosphates, and nitrates — understanding what is considered the “preferred ranges” and how the chemicals will make the enjoyment of your spa that much easier.

First, let’s start with the “preferred ranges.” They are as follows:

Free chlorine                    2 -4 ppm

Salt Level                        2000 - 3000ppm

pH                                  7.2 – 7.6ppm

Total Alkalinity                 80 – 120ppm

Cyanuric Acid                  60 – 80ppm

Total Dissolved Solids       0 - 1500ppm (after subtracting the salt level)

Calcium Hardness            150 - 250ppm

Phosphates                     0ppm

Nitrates                          0ppm



Free chlorine (FC) is chlorine that is available to combine with contaminants in the water to disinfect and sanitize the water. Free chlorine is a residual disinfectant.

Combined chlorine (CC) is after it has bonded with contaminants. In this state, it is no longer able to continue its sanitizing effect. It has done its job and must wait for additional chlorine to begin disinfecting the water again. Combine chlorine cause the unpleasant chlorine smell in the water, burning of the eyes, irritated skin and other unwanted side effects of swimming.

Total chlorine (TC) is the total amount of chlorine in the spa, that is, the sum of both the free chlorine and the combined chlorine.


Salt is the generator's source to produce chlorine. The Mini uses electrolysis to break down the salt also known as sodium chloride to produce chlorine in the form of sodium hypochlorite and hypochlorous acid. The ideal salt level helps ensure maximum benefits of the conversation of the sodium chloride to chlorine gas. Low levels of salt can hinder the Mini effectiveness.


pH has the most impact on properly balanced water and user comfort. The recommended pH of spa water is slightly alkaline. The ideal range is 7.4 to 7.6. Many things can affect the pH of a spa, including user waste; disinfectants; source water; air-borne debris; water balance chemicals; aeration; evaporation.

pH Related Spa Problems:

   Low pH                                                 High pH

   Corrosive Water                                     Scaling Water

   Etching of Spa Surface                           Clogged Filters

   Corrosion of Metals                                Clogged Heater Elements

   Staining of Surface Walls                        Reduced Circulation

   Chlorine Loss                                        Cloudy Water

   Eye/Skin Irritation                                 Chlorine Inefficiency

To lower pH, you can use muriatic acid or dry acid. To raise the pH you would use soda ash. Control of the pH is essential for the comfort of the bather and the efficiency of the chlorine, as well as the protection of the system components. The method used to control pH is to maintain proper levels of the Total alkalinity (TA).

Total Alkalinity

Total Alkalinity (TA) is a measure of the water’s ability to resist changes in the pH. TA is like an anchor for keeping the pH where it should be. Without proper buffering of the TA, the pH can have dramatic swings from High to Low – known as “pH bounce.” Higher levels of TA, the pH is usually higher than ideal and may become difficult to adjust – this is a “pH lock.”

   Low TA                                          High TA

   Chlorine Inefficiency                        Cloudy Water

   Corrosion                                       Clogged Filters

   Staining                                         Clogged Heater Elements

   Eye/Skin Irritation                           Reduced Circulation

To increase the TA level use baking soda and to decrease the TA use muriatic acid. Adjustments of the TA levels affect the pH levels. It is always best to make significant changes in a couple of steps, testing the water after each modification.

Cyanuric Acid

Cyanuric Acid (CYA), also known as stabilizer or conditioner, acts as a sunscreen to protect the Free Chlorine from sun's ultraviolet rays. Sunlight and heat affect spa water's chlorine level. Ultraviolet rays from the sun can reduce chlorine by up to 90 percent in two hours. Combine that with warm temperature of the spa water, tends to breed more bacteria causes the free chlorine to oxidize faster. If you do not use a spa cover, will need to have CYA in the water. If not the spa will have a hard time holding the chlorine levels.

Total Dissolved Solids

Total Dissolved Solids (TDS) is as the name implies a measure of the total amount of dissolved material in the water. Testing for TDS is by assessing the electrical conductivity of the water with an electronic meter.

TDS comes from many of the chemicals we use to keep our spas in balance. Every time you adjust the pH, add conditioner, algaecides, or chlorine, the TDS levels increase. As the TDS levels climb above the recommended 1500 ppm (after subtracting the salt level), your water may become cloudy, and your chemicals become less effective.

Higher water temperatures and aeration in spas result in water evaporating at a faster rate than pools. And it does not remove the minerals or TDS in the water. As the TDS levels increase, chlorine may become less effective causing cloudy water or algae growth. Also, with spa water, the heater elements are more easily attacked by water, and unsightly staining may occur.

To reduce the TDS level the most practical solution is to drain some water and replace it with fresh water.

Calcium Hardness

Calcium Hardness is the measurement of the amount of calcium and magnesium in the water. The recommended range for total hardness for spas is between 150 and 250ppm.

High level of calcium hardness makes it difficult to properly dissolve chemicals in the water while causing scaling in the spa and plumbing. Now when the calcium levels are too low, it could cause erosion, damage and over time eat away at the plaster, plumbing, jets, and other equipment.

It is essential in having the right levels of calcium hardness. It helps improve the chlorine generator's ability to stay clean and provide softer silkier water for the spa bather.


Phosphates and Nitrates set very high demand for chlorine. Most often they bring the chlorine level down to zero and hinder the generator from getting the level back up. You can have the water tested for phosphates and nitrates at a local pool store. When having a chlorine problem, first need to check these two levels, the majority of the time they can be the culprit.

Use a phosphate remover to remove phosphates from the water. Now to remove nitrates is different. You will need to dilute the water with fresh water.


Powered by Zendesk