The original and best selling barley straw pond treatment from Summit. Each bale treats 500-gallon. 2 bales per package. 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. Works up to 6 months.