Understanding Water Balance

Hot Tub Header Mask

FROG Experts teach you how to balance your Hot Tub


To have healthy, sparkling hot tub water requires that your water is sanitized and balanced. These two concepts are equally important in creating a hot tub that you can enjoy. Sanitizing is the process of destroying microorganisms and bacteria – we’ll learn more about this further into the Water Chemistry section.

Balancing your hot tub’s water chemistry is the #1 most important factor to maximizing the life and appearance of your hot tub. Whether you realize it or not, your hot tub’s water is delicate and needs to be balanced. Out of balance water chemistry, whether it’s pH, calcium hardness or Total Alkalinity can not only make relaxing in the hot tub uncomfortable, it can also permanently damage the walls, equipment and other surfaces around your hot tub.

While there are many different levels to measure within your hot tub, the three most important levels to keeping your water chemistry balanced are, Total Alkalinity, pH, and calcium hardness. The table below illustrates the optimal ranges for basic water chemistry.

Spa School Water Balance

Factors that Affect Your Hot Tub’s Water Balance
There are many factors that affect the water chemistry of your hot tub; some are more easily controllable than others are, and some affect the chemistry of the hot tub water more significantly than others do. Regardless of the type of hot tub you own, whether it’s an in ground or portable, the factors that affect your hot tub’s water balance are ultimately the same. While things such as frequent and heavy usage, organic matter and water temperature can all alter the water chemistry within your hot tub, they typically are the least significant factors affecting the water balance. It’s the levels and chemicals you are constantly adjusting (i.e. pH, Total Alkalinity and calcium hardness) that have the most significant impact on your hot tub’s water balance.

The Importance of Balancing Your Hot Tub Water
Water balancing is simply the relationship between different chemicals in your hot tub; balanced water is, neither corrosive nor scaling. Your water is constantly changing, seeking its own level by dissolving and “holding” minerals until it becomes saturated, and cannot hold any more. Hot tub water that doesn’t have enough minerals dissolved is typically more acidic and aggressive, and will attempt to saturate itself by dissolving everything it comes in contact with, in order to build up its mineral content. As a result, the water will begin to corrode and etch away walls, surfaces, and anything metal, including heating elements, pump seals, internal parts on gas fire heaters, underwater light fixtures/jets, etc.

Once hot tub water becomes fully saturated, it will attempt to lose any excess minerals, particles/material in the form of scale, which is then deposited on things the water comes in contact with. Hot tubs that are oversaturated often look cloudy and murky because of the excess particles floating freely in the water, and are at the greatest risk of scaling. If not corrected, scale and carbonates can build up on hot tub filters, in pipes, pumps, etc., decreasing water circulation and ultimately damaging hot tub components.

Simply stated, water balance is a term used to describe the ideal condition of hot tub water. “Balanced” water has just the right level of pH, Total Alkalinity, Calcium Hardness and dissolved solids in relationship to its temperature. To calculate if your hot tub water is balanced check out our Langelier Saturation Index (LSI) calculator.


Sanitizing Your Hot Tub
Keeping your hot tub water balanced not only protects your surfaces and equipment from corrosion and scaling, it allows your hot tub’s sanitizers to work more effectively.

One of the biggest factors that influence your sanitizer’s (let us use chlorine in this instance) ability to effectively clean the water is your hot tub’s pH level. In a hot tub where the pH level is below 7.2, chlorine dissipates much more quickly, which translates into a larger chemical expense and more time spent adding sanitizers to your hot tub. On the other hand, if the pH level is higher than 7.8, chlorine loses its ability to sanitize the water, forcing you to use more chlorine to achieve the same concentration as a hot tub with a balanced pH level. For example, at a pH of 8.2, chlorine concentration can only reach 15%. This means that if you only had to add one dose of chlorine at a pH of 7.2, at a pH of 8.2 you would need to add 5x that amount to achieve the same chlorine concentration.

One of the nice things about using bromine is it is not as dependent on proper pH balance as chlorine is, but for all other reasons, you want to keep your bromine hot tub properly balanced.

Constantly balancing and sanitizing your hot tub can seem like a lot of work, especially if you don’t use it consistently. However, simply keeping your hot tub’s water chemistry balanced and the sanitizer level in check can help your hot tub last even longer and save you the hassle and expense of having to replace hot tub equipment down the road.

If you want to make water chemistry even easier, check out FROG Fresh Mineral Water Systems that sanitize and help maintain pH balance for cleaner, clearer and softer water with up to 50% less chlorine.