What is total alkalinity?

Total alkalinity is a measurement of water's ability to neutralize acidity. This ability can be influenced by various ingredients in water, including hydroxide molecules1 and dissolved calcium. Since total alkalinity serves as a 'buffer' against acidity, it is sometimes referred to as “buffering capacity.”

Why test it?

Measuring total alkalinity helps you better understand the pH balance test (which comes next) and informs which water balancing products you may need to use. Ultimately, it helps to maintain water clarity and avoid eye, nose and skin irritation, plus it protects internal hot tub components.

How is it measured?

Total alkalinity is measured in parts-per-million (ppm) using a test strip. The target range is 80 to 140 ppm.

  • Why is “low” total alkalinity bad? Total alkalinity measuring below 80 ppm makes it difficult to stabilize pH, and a low reading helps to diagnose low pH (which is tested next) or pH instability (also known as “pH bounce”). Because low pH (acidity) can irritate your eyes, nose and skin, and reduce the effectiveness of sanitizers, it is important to maintain total alkalinity in the target range.
  • Why is “high” total alkalinity bad? Total alkalinity measuring above 140 ppm usually increases pH above its target range, which can irritate your eyes, nose and skin, and reduce the effectiveness of sanitizers. High total alkalinity can also cause cloudy water and calcium buildup (or, "scaling").

Need help?

Use two clean water bottles to collect these samples: 1) a water-supply sample from your water source, and 2) a mid-depth sample of your hot tub water. Seal each sample tightly, label each one, and bring them to your nearest Marquis Dealer for testing. They can recommend the right Marquis-approved water care products to keep your water balanced, crystal clear, and feeling great.

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What is total hardness?

What is pH balance?

Testing sanitizer levels

1Hydroxide molecules form when H2O loses a hydrogen ion and forms a different chemical structure (OH instead of H2O).


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