Premium Fertiliser is added each week when changing the water. A flask is used to ensure an accurate dosage. The fertilizer is forced up into the fertilizer chamber by a single press on the flask. We recommend 5 mL per 50 L water per week, but recommend that this is set in accordance with plant requirements. For example, light leaves often indicate lack of nutrition, but can also be due to poor growth. Echinodorus bleheri is a typical example of lack of micro-nutrients. Regular dosing with Premium Fertiliser can restore green and luxuriant leaves. Note, however, that Premium Fertiliser is a fertilizer and not a medicine for dying plants.