Alkalinity in freshwater with the Hanna checker
What is it? Alkalinity in freshwater refers to the water’s capacity to neutralize acid or resist decreases in pH.
Why is it important? The alkalinity of the water is environmentally important because it helps to keep fish and other aquatic animals within the range of acidity that they are able to tolerate.
What does it mean? Water alkalinity is measured in terms of an equivalent concentration of calcium carbonate in a water sample:
- 10 mg/L: Very Low
- 11-50 mg/L: Low
- 51-150 mg/L: Moderate
- 151-300 mg/L: High
- > 300 mg/L: Very High
How to test
The Hanna Alkalinity Checker is a digital colorimeter that provides precise alkalinity readings in ppm (parts per million) as CaCO₃, commonly used in saltwater and freshwater monitoring.
- Rinse the glass cuvette (sample vial) 3 times with your water sample.
- Fill the cuvette to the 10 mL line with your sample water. Wipe the outside with a clean cloth to remove smudges or water spots.
- Insert the cuvette into the Checker, close the lid, and press the button once. The screen will show “C1”.
- Remove the cuvette and add one packet of the Hanna reagent powder (Alkalinity Reagent HI-775-0).
- Cap the cuvette tightly and shake gently until the powder is completely dissolved. The solution should turn a light blue color.
- Reinsert the cuvette into the Checker, close the lid, and press the button again.
- After a few seconds, your alkalinity result will appear on the screen in ppm CaCO₃.
Tip: Make sure the cuvette is clean and dry on the outside before each reading, and always use the same cuvette for best accuracy.