If you are using a gang valve or T-splitter to share one air pump with multiple devices, sometimes air does not travel down all of the outlets. One of two things could be happening. In the first case, your pump is not strong enough to push air into more than one outlet. In the second case, the air always chooses the path of least resistance, so you need to use air valves on each path to ensure that air reaches all the devices.
- Connect the air pump, gang valve, and air-driven devices (e.g., sponge filters, air stones, aquarium decorations) using airline tubing. Plug in the air pump.
- Turn OFF any valves that don't aren't being used.
- For the valves that are being used, turn them ON all the way.
- One of the valves should be bubbling and getting air. Slowly close that valve until the other valves start to bubble as well.
- Adjust the valves until they are balanced and everything is getting air.
Remember that the more valves that are being used, the less air each device will receive and therefore the less bubbling you will see.