Why is My Fish Tank Air Pump Not Working (2024)

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The main reason to use an aquarium air pump is to agitate (aerate) the water inside the tank. It is a simple device that helps to introduce oxygen (O₂) and remove carbon dioxide (CO₂).

But, what if the pump stops pumping? This help guide explains the common causes of fish tank pump failure with some quick and easy fixes to get it working again.

What to Do if No Air is Going into the Tank?

First, let's begin by confirming how much oxygen fish actually need to stay alive.

Most aquarists say the level of Dissolved Oxygen (DO) in water should be at least five (5) parts per million (ppm) for fish health care.

In other words, if the oxygen level drops below two (2) ppm, your fish may be in immediate danger of dying. Hence, you'll need to find a way to get it aerated.

You can use a Dissolved Oxygen Meter to determine the exact oxygen concentration inside your aquarium.

Pro Tip: Another section contains a list of reasons why a Top Fin filter may not be working efficiently, and how to troubleshoot the most common fixes.

Aquarium Air Pumps: Basic Checks

One common reason why fish tank pumps suddenly stop working is a loose or broken air tube connection. So, start the problem solving process by making sure all the air pipe connections are secure.

Next, try to confirm that your pump has a functioning power supply. The easiest way to check this is to disconnect the air pipe from the pump assembly and feel for a slight rush of "wind" coming out of the outlet. If not, you might need to buy a replacement pump.

Pro Tip: Remember, the best aquarium air pumps come with a guarantee of at least one year. So, you should be entitled to a free replacement if your submersible pump breaks down in the first twelve months.

Troubleshooting a Faulty Fish Tank Pump

As already stated, a lack of oxygen bubble aeration of the water in an aquarium is going to be detrimental for fish health.

So, let's look at some reasons why a fish tank pump malfunctions and how to fix it. In particular, you may need to:

• Clean the pump
• Replace a damaged motor shaft
• Repair a torn or broken power head wire
• Replace a defective rubber gasket

In fact, regular cleaning of the pump will reduce the likelihood of it getting dirty and blocked. But, if a power surge damages the motor inside the aerator you may need to buy a new one.

Cleaning a Clogged Air Pump

• Always disconnect electrical devices from the power supply and remove the plug from the outlet before you try to unclog the internal workings.
• Next, pull the soft air tube away from the power head and remove it from the water. Open up the pump and you should be able to see the rotor blade (e.g. the impeller).
• You may need a screwdriver to remove the impeller. Then, you can use a stiff brush to clean algae off the inside of the housing.
• It's best to soak the pump unit in hot water for a minimum of twenty (20) minutes. You can also use distilled white vinegar to clean a badly clogged fish tank pump.

Pro Tip: Another guide lists the common reasons why a fish filter is making a weird noise, how to troubleshoot the cause, and then fix the problem.

Changing a Broken Motor Shaft

• Remove the pump from the water and plug it into the power outlet. Then, take out the broken shaft and turn the power back on. Check if it's magnetised by inserting a tester (or a metal screwdriver).
• This process pulls the tester to one side if it is magnetised. If you buy a new shaft, you may need to use a set of pliers to cut it so it matches the size and radius of the broken shaft. Sometimes, you may also need to file the edges so they are smooth.
• Put the new shaft back inside the impeller and reassemble the parts in the reverse order. Put the pump back together and check for proper function.

Repairing a Power Head Wire

• The first part of the process is cutting the broken wire. Then, cut the black wire and remove both wires (e.g. black and red).
• Insert the two plastic tubes at the plug and the pump end. Next, use a small blowtorch (or cigarette lighter) to heat the tubes.
• Apply a strong epoxy adhesive onto both wires and the tubes. Let it dry and then apply some silicone glue over the adhesive and the tubes.
• Repeat the same process for the plug and then make it waterproof by wrapping it with plastic tape. Cover it with a plastic tube and then use a heat source to secure it in place.

Replacing a Rubber Gasket

Dismantle the pump assembly and disassemble the air cylinder to reveal the rubber gasket. Use a screwdriver to take it out and then replace the new rubber gasket.

Conclusion and Safety Tips

• Use extra caution when you clean the small thin blades of air pump impellers. Applying too much force can break them.
• Wear heat resistant gloves when you use fire to soften the plastic tubes.
• It's a good idea to have some extra tubing in case you decide to change the pump location while you reinstall it.
• Install a check valve to stop water from leaking and a drip loop will help to prevent water from entering inside the power outlet.

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