Treats 11,250 litres. Instructions: Use 10ml per 225 litres or 50 gallons of water. 1. Shake the bottle. 2. Remove the cap which is not on the measure. 3. Squeeze the bottle gently until you reach the required amount. 4. Treat weekly if you have problems than every 2 weeks during the spring and summer. This extract helps to neutralise and clear green water and blanket weed in ponds making it the perfect solution to keep your pond clear. The natural extract works faster than using actual barley straw. This barley straw extract is 100% organic and is the perfect solution to keep your pond clear.