Control green or brown water in your saltwater aquarium_x000D_ dr.Tim's re-fresh is a potent combination of beneficial bacteria that work together to maintain clear water, clean aquarium surfaces and eliminate unpleasant odors. Re-fresh revitalizes green or brown aquarium water and keeps your water crystal clear! Keeps surfaces clean_x000D_ maintains water clarity_x000D_ choose the size best suited for your system:_x000D_ 4oz bottle treats 240 gallons (908 liters)_x000D_ 8 oz bottle treats 480 gallons (1,817 liters)_x000D_ 16 oz bottle treats 960 gallons (3,634 liters)_x000D_ 32 oz bottle treats 1,920 gallons (7,268 liters)_x000D_ 64 oz bottle treats 3,840 gallons (14,534 liters)_x000D_ 128 oz bottle treats 7,680 gallons (29,069 liters)_x000D_ re-fresh should be added on a weekly basis to help maintain a clear, clean and sparkling aquarium. Because the condition of every aquarium varies, it may be necessary to add re-fresh more frequently (every other day) to achieve desired results. D