NT Labs GH & Minerals UP has been designed to increase the hardness of the water in your pond and keep essential biological processes working well. To avoid stagnating and acidification of the water maintain a water hardness of 8JDh to ensure that the levels of calcium and magnesium are at the desired level for a healthy pond. Calcium and magnesium are vital components for healthy plant growth and micro-organisms that consume miniscule algae cells keeping your pond crystal clear. Dosage Instructions: To increase the GH of your pond water by 3-4dH use 50ml to 340 lts of pond water. Dissolve the product in a bucket of pond water ensure fully dissolved before adding directly to the pond. 3 sizes available; 1.5kg 5kg 20kg.