Potassium

Potassium plays an extremely important role in the ion balance of all living organisms, from simple bacteria to mammals. A multitude of physiological processes is not possible without potassium: stimulus transmission of cells, protein utilization, protein synthesis, acid-base balance, cell growth.

In reef aquaristics, the ratio of potassium to sodium should be correct in order to maintain healthy corals. Potassium is incorporated into the coral skeleton as potassium carbonate or organically bound. The amount of potassium incorporated into the coral does not reflect the seawater composition and is temperature and species dependent. Elevated potassium concentrations can trigger metamorphosis of marine larvae by directly affecting cell membrane potential. A potassium chloride-storing organelle (Kalisome) in coral larvae is discussed.

Potassium sources:
Sea salt, potassium additives, potassium iodide (iodine dosing) or iodine potassium (Lugol's solution) in dip solutions.

Natural seawater concentration: 380...390 mg/l (at 35 PSU).
Recommendation for seawater aquariums: 390...430 mg/l (at 35 PSU)