Barley straw has been used for hundreds of years to promote clean clear water conditions in ponds and streams. EcoBarley Liquid Extract is a pharaceutical-grade, fermented barley extract that has been concentrated to give you a clean clear pond. The added enzymes will help reduce pond maintenance by breaking down pond sludge and keeping filter pads cleaner. Available in four sizes: 250ml/8.5 oz, 500ml/16.9 oz, 1 liter/33.8 oz,4 liters/1 gal.