What Is an Aquarium Water Pump and How Does It Work?

Posted by
John Woodard on June 16, 2022

Just like humans need air circulation to breathe properly, fish require water circulation and aeration to maintain their health. While aquarium filters provide some circulation to your tank, water pumps play a big role in keeping water moving and fostering robust marine life. Aquarium water pumps allow your fish to receive the oxygen and nutrients they need to maintain long, healthy lives. Below you can find information on what aquarium water pumps are, how they work, their types, and how to maintain them.

What is an aquarium water pump?

An aquarium water pump is a fish tank accessory that aerates and circulates water to make it healthier for marine life. The current produced by a water pump ensures that all water in a tank feeds through the tank’s filter. This constant flow evenly distributes nutrients throughout the tank, creating high-quality water that prevents diseases in fish. Not only do water pumps produce health benefits, but they can also make your tank aesthetically pleasing. A water pump brings your tank to life by making plants dynamic as they wave with the increased water flow.

How does an aquarium water pump work?

The impeller, a series of vanes surrounded by one or two solid plates, is the heart of an aquarium water pump. An electric motor spins the impeller to create kinetic energy. An intake port sucks water in, and the impeller’s kinetic energy transfers to the water. This energy forces the water into the tank, where it circulates into the tank’s filter and eventually makes its way back into the pump. The current produced by the pump ensures that all water in a tank is in motion, eliminating the risk of stagnant water compromising the aquarium’s quality of life.

Do I need an aquarium water pump?

Aquarium water pumps are more beneficial to larger tanks than they are to smaller aquariums. As a result, not all small tanks need a water pump. A regular aquarium filter provides sufficient flow for smaller tanks, but larger aquariums need the additional help of a water pump. If you notice sluggishness in your fish or algae growth on your aquarium’s surfaces, low circulation may be the cause. If these symptoms persist when your tank’s water contains appropriate chemical levels, a water pump may be your solution.

What is a good flow rate for my aquarium?

An aquarium water pump’s flow rate should be at least five times higher than the volume of the tank. For example, if your aquarium holds 40 gallons, you will want to invest in a water pump with at least a 200 GPH (gallons per hour) flow rate. However, the advertised flow rate of a water pump is the maximum flow rate when no obstacles are involved. These obstacles can reduce the flow rate of a pump greatly and, as a result, affect the flow of the aquarium. Factors that impact the flow rate of a pump include the height of the pump head, indirect routes in plumbing, and the size of inlet and outlet tubing used. You can attempt to mitigate these factors, or you can purchase a water pump that produces a flow rate higher than five times the tank’s volume.

You will want to make sure that the flow rate of your pump is not too high for your tank. This can cause too much circulation that can harm your fish or force water out of the tank. Many pumps come with adjustable flow rates and timers that ensure the flow is ideal for your tank size.

Types of aquarium water pumps

There are two main types of aquarium water pumps, submersible and in-line.

Submersible water pumps

Submersible water pumps are designed to run inside a tank’s water. They are easy to install and maintain compared to in-line pumps, but they rely on the aquarium’s water for cooling. Submersible pumps dissipate heat into the tank’s water, meaning that fish that are sensitive to temperature changes can be negatively affected.

One big advantage of submersible pumps is their quiet operation. Because they are placed in a tank, water absorbs the motor’s sound. This allows for peaceful, effective circulation in your aquarium. Some submersible pumps also contain filters that clean dirt and other debris from a tank’s water. Other submersible pumps include features such as timers, gages, LEDs, and controllers for flow rate and noise.

In-line water pumps

In-line water pumps, also called external pumps, are not waterproof and sit outside an aquarium. Inlet and outlet tubing route water to and from the pump. Unlike submersible pumps, in-line water pumps do not dissipate heat back into the tank, so fish will not suffer adverse effects from constant temperature changes. If you have other pets or small children, they may be tempted to mess with the tubing on an external pump and consequently compromise the health of your aquarium. Ensuring that your pump will not be disrupted is essential in maintaining the health of an aquarium with an external pump.

One disadvantage of in-line water pumps is the effect gravity has on them. Since water must be piped out of the tank to be pumped back in, the pump’s inlet and outlet must be powerful enough to feed water into the pump and out of the tank. Choosing the proper location for your in-line pump can mitigate the effect of gravity, so optimizing your setup is crucial in running an efficient pump. Another disadvantage of in-line pumps is the noise they create. Because they are placed outside of a tank, there is no water to suppress the motor’s sound. As a result, in-line pumps are much louder than submersible pumps.

How to clean an aquarium water pump

An aquarium water pump should be cleaned at least once every 4 to 6 months in a fish-only tank and once every 2 to 3 months in a reef tank. To clean a pump, follow these steps:

  1. Turn off your pump and unplug the power source.
  2. If you are cleaning an external pump, remove the inlet and outlet tubing.
  3. If your pump is in a sump, remove it from the controller and sump.
  4. Remove the main housing from the pump. Some pumps may contain screws, while housings in other pumps can simply be twisted off.
  5. Remove the impeller.
  6. Clean the impeller and housing of the pump with fresh water. You can use a toothbrush to eliminate hard-to-remove debris.
  7. If there is calcium on your pump, create a solution with one-part muriatic acid for every three-parts citric acid. Allow the pump to soak and rinse thoroughly.
  8. Allow the pump to dry.
  9. Reassemble the pump.
  10. Reconnect the power and tubing if applicable. Your pump is ready to use.

Aquarium water pump vs air pump

Aquarium water pumps and air pumps add similar contributions to tanks, but they offer some unique features as well. An air pump adds air to a tank directly in the form of bubbles. Water pumps, on the other hand, aerate a tank by increasing surface agitation. The current created by water pumps allows air to enter the water at the surface of a tank more quickly than if the water were slower moving.

Noise levels are another difference between water and air pumps. In-line water pumps and air pumps both produce a fair amount of noise, but submersible water pumps can run silently. A silent option for air pumps is an air stone. However, air stones do not provide as much oxygen as pumps do, but they do provide less aggressive smaller bubbles.

Both water and air pumps increase circulation in a tank. This allows the tank’s filter to input and output water at a constant rate. Some species, such as bettas, prefer very little movement in their water. As a result, air and water pumps are not beneficial to them.

Learn more: What Is an Aquarium Air Pump and Is It Necessary?

Aquarium water pump cost

An aquarium water pump’s cost increase with its flow rate. An EcoPlus 290 GPH submersible pump, for example, costs $25, while a 396 GPH submersible pump costs just under $45. Large water pumps, such as this 1900 GPH flow pump, run at around $160. If you choose to buy an external pump, you will also need to purchase airline tubing to feed your pump. While this is an additional cost, it should not cost you more than $5. Some pumps, such as the Uniclife 800 GPH pump, can be used as either in-line or external pumps.

Benefits of reverse osmosis water with aquarium water pumps

Reverse osmosis water is excellent to use as a base for your aquarium. It eliminates contaminants such as nitrates, phosphates, silicates, and hardness. Not only does this help your fish live healthier lives, but it can also increase the lifespan of your pump. If calcium is present in an aquarium’s water, it will build up on your pump’s motor. Over time, this can cause the pump to perform poorly. Using a reverse osmosis filter before introducing essential minerals into your aquarium is an excellent way to protect your fish and tank accessories.

Explore how water quality can affect your aquarium: Why You Should Use Reverse Osmosis Water for Your Aquarium

Does an aquarium pump need to run all the time?

Yes, both water and air pumps in an aquarium should run constantly. They both serve as life support for the aquarium, so fish and plant life will suffer if they are turned off.

Learn more about aquarium maintenance: How to Maintain a Freshwater Aquarium



If you have any further questions, please do not hesitate to contact us.

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