Betta Water Conditioner Block 15g helps stablise pH levels and neutralise ammonia. It is the ideal block for keeping your BETTA's water healthy. Place the block in the bowl or tank, it will slowly dissolve. Use when setting up your BETTA tank or when changing the water. One whole block will treat 120 litres & one piece will treat up to 20 litres. All fish benefit from a regular water change, always use water conditioner to treat tap water before adding to your tank. Regularly check pH levels in your tank, it should be approximately 6.8 to 7.2.