In natural seawater, potassium is a non-conservative major element with a concentration slightly lower than that of calcium (~399 ppm vs. ~413 ppm, respectively). It is a component of aragonite, and regular dosing has, within the past several years, been implicated in improving the blue coloration of numerous varieties of small-polyp stony corals; the benefits of potassium supplementation are potentially two-fold, then: provision of an element that is 1.) incorporated into the skeletal material of corals and other reef-buidling organisms for purposes of growth, and 2.) incorporated into pigments that (presumably in the presence of adequate ionic iron) enhance blue coloration of small-polyp stony corals. The importance of potassium to marine organisms is most apparent when beginning to dose it in aquaria with depleted potassium concentrations and/or in which the sea salt mixture used is potassium-deficient; in such cases, changes in the appearance of many corals may be observed within the first weeks of regular dosing.
Maintaining potassium within a range of 390 - 410 ppm is sufficient for long-term health, growth, and coloration of corals when all other physical and chemical requirements are met. The rate at which potassium is extracted from the water is determined by the stocking density of potassium-depleting livestock, characteristics of lighting and method(s) of filtration employed, and other biological, physical, and chemical conditions; therefore, each aquarium will have different requirements for the rate of potassium supplementation. Once the rate of potassium uptake in the aquarium has been determined (see opposite), the proper dosing rate of this product can be easily calculated.
It is recommended that a quality salt mix with the proper (not augmented) alkalinity and concentrations of major, minor, and trace elements be used to establish natural seawater parameters in marine aquaria, providing a stable ionic foundation on which to build.