Air Stones circulate aquarium water, generating oxygen whilst providing environmental enrichment.
Ensure a check valve is in place. This will stop water from siphoning out of you aquarium if the pump fails.
If the Air Stone stops working correctly, remove it from the aquarium and clean in warm water, or replace it. Check the operation of your air pump as the diaphragms or flapper valves inside the air pump may have deteriorated.
Before purchasing an air pump, consider the depth of your aquarium, the number of ornaments and the size of the Air Stone you wish to operate.