Zoolek Aquatest K

Zoolek Aquatest K is a complete kit for determining the concentration of ions potassium (K) in fresh water. It enables the measurement of in the range of 3 to 125 mg/l, enabling accurate monitoring of one of the essential macronutrients responsible for the proper metabolism of aquarium plants.

Why measure potassium?

Potassium (K), alongside nitrogen (NO₃) and phosphorus (PO4), is one of the most important macronutrients essential for proper plant growth.

Unlike nitrogen and phosphorus, which are often present in sufficient or even excessive quantities in fish tanks, potassium is very rarely supplied in sufficient quantities naturally.

Failure to monitor potassium levels leads toa gradual deficiency, which manifests itself asyellowing of older leaves, the appearance of characteristicholes in the leaf blades and a general weakening of plant growth.

A potassium deficiency also disrupts the transport of other nutrients within plant tissues, impairing their condition even when levels of NO₃ and PO₄ are normal.

On the other hand, excessive potassium supplementation is not without consequences either. Although high concentrations K is not toxic to fish and shrimps, but may lead to impaired absorption of other elements, such as calcium, magnesium or trace elements, causing secondary deficiencies.

Responsible aquarium keeping

For most aquarium plants, the optimum potassium level is between 10 and 20 mg/l, although its consumption depends primarily on the number of plants in the tank and their growth rate.
Regular testing of K levels allows you to fine-tune fertiliser application rates, maintain a stable balance of macronutrients and provide plants with conditions conducive to healthy, even growth without the risk of deficiencies or excesses of nutrients.

The Zoolek Aquatest K is designed for freshwater aquariums, in particular planted aquariums and aquascape set-ups, where potassium is supplemented independently of nitrogen and phosphorus. It works well both in aquariums with a moderate number of fish and in tanks with a high density of plants, which require regular monitoring of potassium levels.

Zoolek Aquatest K It is fully equipped and ready for use. There are enough reagents to carry out 25 tests.

Contents of each product:

– a container containing a powdered reagent
– a bottle of demineralised water
– spatula
– 2 plastic test tubes
– syringe
– pipette
– illustrated guide
– guidelines

Tip 1
Potassium consumption in an aquarium depends mainly on the number of plants and their growth rate. In tanks with high stocking densities or where CO₂ is applied intensively, the CO₂ level K may decrease more rapidly than in aquariums with fewer plants.

Regular testing allows for precise adjustment of fertiliser application rates and helps maintain the optimal range of 10–20 mg/l, which promotes healthy and stable plant growth.

That is why fertilisation based on regular measurements, rather than on fixed, ‘rigid’ doses, yields the best results.

Tip 2
If you are struggling with excess potassium (above 20 mg/l), more frequent water changes in the aquarium or reducing the amount of potassium (K) added can be effective measures.

Advice 3
If the potassium (K) level in the aquarium is too low (below 10 mg/l), which can lead to yellowing of the leaves, the formation of holes in the leaf blades and stunted plant growth, it is worth considering controlled supplementation of this element. In such cases, the following works well: Clarity K, which allows you to top up this element in your aquarium water.