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Salifert® KH/ALK Profi Test Set

Delivery Time
approx. 2-5 working days (Mon-Fri) abroad different
Incl. 19% VAT, excl. Shipping Cost

Salifert® KH/ALK Profi Test Set - Water test set for the determination of carbonate hardness.

Test and addition of alkalinity

Calcium alone cannot form the skeletal material of corals and grow calcareous algae. Some other components are also needed. Some other components are carbonate and bicarbonate. These two substances also have a great impact on stabilizing the pH in the proper range of 8.1 - 8.4. Such stabilization is also called buffering.

The total concentration of carbonate and bicarbonate is also called carbonate alkalinity or carbonate hardness. The only difference between alkalinity and carbonate hardness is a conversion factor.

Natural seawater has an alkalinity of about 2.7 meq/L or about 7.5 dKH, expressed as carbonate hardness.

For a stable system, the alkalinity or carbonate hardness should have a value similar to or slightly higher than natural seawater and preferably should not fluctuate by more than 5%. This means a maximum fluctuation of 0.14 meq/L or 0.4 dKH.

Therefore, an alkalinity test kit should be able to measure in increments smaller than 0.14 meq/L. Salifert® KH/ALK Profi Test is able to do this.


Since the main buffer components used for coral and calcareous algae growth are bicarbonate and carbonate, they should be added to correct any decrease in alkalinity or carbonate hardness.

A properly composed buffer should function in such a way that the corrective action results in a long-lasting effect and does not upset the pH of the system. Alkalinity or carbonate hardness should be kept as stable as possible, which requires highly sensitive and accurate test equipment.

The Salifert® KH/ALK Profi test is very straightforward. It measures in sufficiently small steps of 0.1 meq/L or 0.3 dKH with a clear color change. This allows the detection of important but small changes.

Approximately 100 - 200 measurements can be performed with the Salifert® KH/ALK Profi Test Kit.

The Salifert KH + pH buffer makes the correction of alkalinity or carbonate hardness easy and does not disturb the pH of the system. Within 24 hours, it reaches the pH value that corresponds to the other aquarium parameters. If the pH remains low within 24 hours after correction, insufficient gas exchange (inefficient aeration) is often the cause.