What You Need To Know About Water Balance

Aug 13, 2020

Keeping a swimming pool clean and ready-to-use isn’t just about cleaning out the occasional leaf. Water balance is a critical part of swimming pool health, both for the pool and you. Maintaining the proper water balance is easier than it seems, and it will make a world of difference to you and your family’s enjoyment and the lifespan of your swimming pool.

Why Water Balance is So Important 

Having the right chemical balance in your pool’s water helps to ensure your swimming pool is a healthy and safe place for you and your family. When the chemical balance of the water is off it can cause unhygienic water quality and skin irritation. 

Correctly balanced water will also safeguard the pool shell, prolonging the life and maintaining the quality of the finish. Imbalance in the chemical composition can cause build-up and corrosion on the pool’s interior and equipment, ultimately causing expensive or irreparable damage. 

Maintaining Water Balance 

Measuring pH 

The pH level of your swimming pool is a measure of the acidity or alkalinity of the water. The pH scale ranges from 0 to 14, with values above 7 indicating too much alkalinity and values below too much acidity. Standards for fibreglass swimming pool shells recommend a target value of between 7.0 and 7.4 i.e. neutral on the pH scale. 

Many factors can influence the pH level of your pool water such as rainfall, maintenance, cleaning, and water top-up. It is, therefore, important to check and adjust the level regularly to keep your pool well balanced. The wrong pH level can cause health problems such as itchy skin and inflamed eyes, as well as inhibiting the ability of the pool filtration and sanitisation process.

Total Alkalinity

Total Alkalinity, often referred to as simply T.A., measures, in parts per million (ppm), the number of important balancing chemicals in the pool water. The total alkalinity measures the levels of hydroxides, carbonates, and bicarbonates, all of which are required for a healthy and well-balanced pool. 

Too low a T.A. level can result in damage to the pool shell’s surface, and lead to fast changes in the pH level of the water. Keeping the T.A. level within the desired range is a balancing act. Buffer agents will raise the T.A., and acid will lower it, but you must be careful to balance these changes and monitor them alongside the pH level of the water. 

Narellan Pools recommends a Total Alkalinity range of 80-120ppm for its pools. Around 100ppm is a good target.

Calcium Hardness 

Calcium hardness is the level of calcium dissolved in the pool water. Your Narellan pool water should have a calcium hardness level of 100 – 300ppm. Too little calcium in the water will lead to an imbalance and risks the calcium in the shell and surrounding plaster being dissolved and leached into the water. Too much calcium, on the other hand, can cause scaling on the shell’s surface and issues with the filtration system. 

Like total alkalinity and pH levels, the calcium hardness level needs to be carefully monitored and adjusted regularly. If you live in an area with low calcium in the natural water supply, then testing yearly should be sufficient. Be mindful though, if you are using Calcium Hypochlorite to sanitise your pool, the Calcium Hardness levels could increase rapidly, and therefore you may be required to have pool shop testing done weekly. Home test kits generally cannot test for calcium hardness, however, so you will likely have to take a sample to your pool supplier for testing. 

When adjusting the calcium hardness level, be sure to do so in balance with the total alkalinity and pH as changes in one can have a knock-on effect on the others.


The other key component of a water balancing program is sanitiser. Chlorine is commonly used for this process, and it’s available in various forms. Chlorine is bleach, so be aware that excessive amounts of chlorine over a prolonged period of time will bleach not only your swimmers but your pool colour! Narellan Pools’ chlorine range is 1-3ppm.

Contact the team at Narellan Pools to learn more about water balance and your Narellan Pools fibreglass shell.

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