Each month, add 600 g per 5,000 litres of pond water (KH increases by approximately 4°dH). Repeat if required, especially after heavy rainfall or before using anti-algae products and remedies. Overdoses are not dangerous. KH increase per 5,000 l of pond water: 600 g approx. 4°dH | 300 g approx. 2°dH | 150 g approx. 1°dH