Slowly lower the pH of your pond water to make it more acidic using API® POND pH DOWN pH adjuster. This product slowly neutralizes alkaline substances that cause high pH, which limits the ability of aquatic plants to absorb necessary nutrients. POND pH DOWN pH adjuster is safe for pond fish and aquatic plants, and contains no algae-promoting phosphates.
Test the pH level of the pond water with an API POND WIDE RANGE pH TEST KIT. Use the dosing cap on the bottle. Add 5 ml. of pH DOWN pH adjuster for each 50 gallons of pond water. Wait 24 hours, then test pH again. Repeat treatment as necessary.