Unlock the water clearing power of barley straw with this fast acting, effective liquid extract. One ounce treats up to 1000 gallons. Clear-Water Barley Extract begins to work more quickly than traditional barley straw but must be applied more often. Keep your pond water clean and clear year-round. Clear-Water Barley Straw Clarifiers are easy to use, safe and attractive. Clear your pond, fountain and fish tank naturally. Acts as a natural filter to keep your pond clean and clear. Won't harm fish or plants.