Air stone circulate aquarium water, generating oxygen whilst providing environmental enrichment. Direction: rinse the air stone gently in warm clean water to remove dust. Ensure check valve is in place. This will stop water from siphoning out of your aquarium if the pump fails or place the air pump above the water level. Try to keep the air stone level. This will ensure bubble along the entire length of the stone. If the air stone stops working correctly remove it from the Aquarium and clean in warm water, or replace it. Check the operation of you air pump as the diaphragms or flapper valves inside the air pump may have deteriorated.