The performance of continuous renal replacement therapy (CRRT) brings about alterations in the serum potassium levels in patient. Potassium is an electrolyte essential for the regulation of nerve conduction and muscle contraction, particularly important in the case of cardiac muscle. This article describes the physiological mechanisms that affect potassium distribution throughout the body and also describes the effects of hypokalaemia or hyperkalaemia on the heart. This article justifies the need for serum potassium control during CRRT, which recognizes and reconciles the differing areas of responsibility of the medical and nursing staff. This article critically reviews the steps taken to develop and implement into clinical practice and evaluate a potassium additive algorithm. It also discusses the implications of this initiative.