Tropic Marin KH/Alkalinity Test for Seawater

Measuring range: 1 - 20 °dH

Resolution (accuracy): 0.5/1 °dH


The carbonate hardness (KH) or alkalinity of a water sample characterizes its buffering capacity, i.e., its ability to maintain the pH value of the water.

In water chemistry, several terms with different definitions exist to describe buffering capacity. In aquariums, the term "carbonate hardness" is commonly used; however, alkalinity is actually measured. In this test, both terms are used synonymously. Carbonate hardness is usually given in degrees of German hardness (°dH). A conversion table for other common units can be found in the instructions for use.

Carbonate hardness should be checked regularly in all aquariums. If the alkalinity in the aquarium is too low, it can lead to a life-threatening drop in pH (acid crash) for many fish and invertebrates. In reef aquariums, sufficient carbonate hardness is essential for strong coral growth. Conversely, excessively high carbonate hardness in saltwater tanks can lead to calcium carbonate deposits and also negatively affect coral growth.

In a saltwater aquarium, the carbonate hardness should be between 6 and 9 °dH. In freshwater aquariums, the carbonate hardness should not fall below 3 °dH. The optimal alkalinity value for a freshwater aquarium depends on the fish and plant species being kept. Ask your local aquarium shop about the correct carbonate hardness for your aquarium.


Shake the dropper bottle before use!
Rinse the glass cuvette with tap water and then several times with aquarium water.
Using the dosing syringe, fill the glass cuvette with exactly 5 ml of aquarium water.
Now add KH test reagent drop by drop (shaking the cuvette after each drop) until the color of the solution changes from TURQUOISE BLUE to PINK.
The number of drops indicates the carbonate hardness of the solution in °dH, e.g., 8 drops = 8 °dH. To increase the accuracy of the measurement, 10 ml of water sample (instead of 5 ml) can be used. In this case, 1 drop corresponds to 0.5 °dH, e.g., 15 drops = 7.5 °dH.
After the measurement process, thoroughly rinse the glass cuvette and syringe with tap water.
 
Use within 6 months of opening. Store in a cool, dark place.