Potassium/Kalium is one of the most vital nutrients for water plants along with nitrogen and phosphorus. Usually there is not enough potassium in the water and hence we have to supply it artificially. Potassium deficiency can have a negative impact on the growth and appearance of your water plants in your aquarium.
The JBL K Kalium Test-Set is an easy accurate and fast way to measure the potassium levels in your aquarium. It can measure potassium levels between 2.0 and 15 mg/l.