Pisces Banish Blue Water Dye is a cost-effective, long-lasting treatment for avoiding green water and aquatic weeds in garden ponds and water features. It works by blocking light in the water, preventing algae growth and adding rich colour to your aquatic landscape. Banish Water Dye is pesticide and herbicide-free and can be used all year round. How to Use: Shake the bottle and remove the cap. Add 1ml of Banish Water Dye per 60 litres (13.2 gallons) of pond water. Add the dye in early spring before algae begins to grow. Specifications 100ml - Treats 6000L (1320 Gallons).