Water pumps are the backbone of aquarium filtration. The tank is cleaned as the pump moves water through your filtration system. Pumps also help ensure proper gas exchange and healthy levels of dissolved oxygen.

When building an aquarium with a sump or using an all-in-one aquarium, you will often hear the term "return pump." This refers to the main pump that returns water from the sump/filter back into your display tank. There are a wide variety of water pumps available to suit every aquarium application. Today we are going to go over the different types of return pumps to help you choose the right pump for your tank.

Pumps are generally grouped into two categories: submersible pumps (which means the entire pump is submersed in water) and external pumps (which means the pump is mounted outside of the water). Keep in mind that many pumps fall into both categories, so do not let this confuse you. More and more pumps are being sealed so that they are safe for both submersed and dry applications.

Submersible Aquarium Pumps

Submersible pumps are the most popular because they are easy to install and maintain. The pump is completely sealed and safe for operation underwater. All you need to do is connect your plumbing, drop it into your sump or filter and you are good to go! Since the pump is submersed in water, it will generally operate with minimal noise. The exception is large submersible pumps which can be fairly loud. Submersible water pumps should be removed and thoroughly cleaned every few months to maintain optimal performance.

All of the submersible pumps we carry are magnetic drive-type pumps. This design allows the motor to be completely sealed and separate from the impeller which makes for safe operation underwater. Classically submersible water pumps are driven by AC (alternating current) power. Many of the aquarium hobby's favorites like the Mag-Drive, Sicce Syncra and Eheim Universal Hobby pumps are all AC powered magnetic drive pumps.

Thanks to modern technology, DC (direct current) powered submersible pumps are now available. This is a welcome innovation because they operate using less electricity compared to AC powered pumps and allow you to electronically control the speed or flow rate of the pump. They also tend to run quieter and cooler than most AC pumps and are safer for use around water because of the low voltage DC power.

The new Deepwater Aquatics BLDC pumps are DC powered and come with a smart controller that has six preset speeds, a feed mode and automatic dry run protection. Aqua Medic DC Runner and Reef Octopus RODC controllable pumps are also popular choices.

External Aquarium Pumps

External pumps are a little more involved in terms of getting them installed but will offer some great benefits.

You need to have a bulkhead in your sump or filter that will allow water to flow into the pump. External water pumps do not prime themselves and must have a flooded suction line in order to operate properly. External pumps transfer less heat into your aquarium, offer higher flow rates with better pressure ratings and typically last much longer when compared to submersible pumps.

Many of the magnetic drive pumps mentioned earlier can also be installed externally. However, there are a number of larger, more robust magnetic drive pumps that are designed specifically for external use, like Iwaki or Pan World pumps. These pumps use heavier duty, commercial-grade motors that will last a long time. They also handle pressure really well, so they are great for applications with long or complicated plumbing.

When choosing an external pump, you also have the option to use a direct drive pump from brands like ReeFlo or Dolphin. Direct drive pumps are nice because they have cool, quiet, low speed motors that will last a long time—up to 10 years when properly maintained.

Since the shaft completely separates the motor from the impeller, you get minimal heat transfer into your aquarium with a direct drive pump. The motors are generally very reliable but the pumps do have a seal that can wear out over time and will need to be replaced periodically. Direct drive external pumps offer high flow rates and use large diameter plumbing connections, so they are great for larger aquariums and closed-loop systems. Plan out your plumbing carefully and make sure to get all the necessary components before installing.

It is crucial to keep your return pump clean and in good working order, regardless of the application or type of pump. A failed return pump can cause a catastrophic tank crash if you are not prepared with a backup pump or spare impeller.

If you are in the market for a new pump or have questions about aquarium water pumps, please contact our aquarium experts so that we can help you choose a pump that fits your specific application and budget.

Thanks for reading and until next time, take care and happy reefkeeping.

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