Total Alkalinity

What is Total Alkalinity?

Total Alkalinity is a measure of water's ability to withstand a change in pH and is measured in PPM (Parts Per Million) of acid resistant substances. It is made up of bicarbonates, carbonates, hydroxides and other substances that absorb acid.

How do you test for it?

Total Alkalinity can be tested with a standard 4 in 1 test kit, photometer, test strips, or by taking a water sample to your local pool shop. Alkalinity is quite stable and test results will not be affected by a short trip to the local pool shop.

What should it be?

The ideal level for Total Alkalinity will vary between pools but most should be somewhere between 80 - 160 PPM.

• Synthetic surfaces (vinyl, fibreglass): Aim for a higher level of 110 - 160 PPM

• Natural/aggregate surfaces (quartzone, pebblecrete, etc.): Aim for a lower level of 80 - 120 PPM.

Pools with an acid feed are often difficult to maintain to a higher level and you may find it better to maintain these pools to the lower end of the scale. If unsure, consult with your pool or equipment manufacturer.

Why is it important?

Total Alkalinity helps to prevent sudden changes in pH levels. A stable pH is essential for effective sanitisation of your pool and prevention of burns and skin or eye irritation due to a low pH (acidic environment).

How to adjust it

• To increase alkalinity: Add pH buffer (AKA sodium bicarbonate) to a bucket of water and distribute around the pool.

• To decrease alkalinity: Add hydrochloric acid directly to the pool water. Retest after 4-6 hours to ensure the level is within the desired range. Do not swim for 1-6 hours after adding hydrochloric acid

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