How to Choose an Aquarium Return Pump

How to Choose an Aquarium Return Pump

A return pump is essential for creating the ideal aquarium environment. Having an appropriately sized return pump helps create a happy and healthy ecosystem.

What is a Return Pump?

The return pump is critical to keeping your aquarium filtered and healthy. In addition to returning filtered water to the tank, return pumps also provide water flow to other equipment, including chillers, reactors, UV sterilizers, and more.

Return Pump Choices
Return Pump Choices

Why the Proper Turnover Rate is Important

Flow is an important component of a successful reef tank. In nature, corals constantly experience flow. This water flow provides corals with the nutrients and food they need and removes the waste they produce. This principle is also true in aquariums, where corals heavily depend on the water movement created within a system. A healthy turnover rate is crucial because it improves the gas exchange that adds oxygen to the aquarium and removes carbon dioxide. Increasing the turnover rate also improves the efficiency of your protein skimmer and other filtration equipment. Please consult the chart below for our recommended turnover rates.

Type of TankTurnover Rate
Fish Only10-12x Tank Volume
Mixed Reef15-20x Tank Volume
SPS Dominant20-25x Tank Volume
Return Pump Turnover Rate

AC vs. DC Pumps

The chart below lays out some of the key differences between AC & DC-powered pumps.

Differentiating FactorsAC PumpsDC PumpsExplanation
Energy EfficiencyA DC pump will generally use less energy than a similar-sized AC pump
NoiseThere are no significant differences between an AC & DC pump.
ControllabilityAlmost all DC Pumps offer variable speed control, whereas most AC pumps do not.
HeatThe power supply for a DC pump is external to the pump body, which puts less heat in the aquarium.
Durability / LifespanDurability is mainly about the quality of the components and the manufacturer, not whether it is an AC & DC pump.
SafetyA DC pump uses less voltage than a similar-sized AC Pump
AC vs. DC Pump Comparison

General Recommendations

  • While both are solid options, we generally prefer a DC model for improved energy efficiency, reliability, and control.

Internal vs. External

Over the years, one noticeable change in return pumps has been the shift from an external to an internal build. Initially, most return pumps were positioned outside the sump and had PVC or another type of tubing that provided the source water. Today, most return pumps are submersible and sit inside a sump or filtration chamber. However, submersible pumps are limited in size, so hobbyists with massive systems tend to use an external pump.

Internal and External Return Pumps
Internal and External Return Pumps

General Recommendations

  • An internal/submersible return pump is the best choice for most standard aquariums.
  • A submersible return pump reduces the chances of any leaks.
  • An external pump may be a better option for tanks over 500 gallons.

Selecting the Proper Size

To properly size a return pump, you will need to know the target flow rate and estimated head pressure on the return pump. Calculate the target flow rate by multiplying the target turnover rate by your tank size. Calculating the estimated head pressure is more complicated. The head is the amount of resistance required to pump water from one location to another. The most significant factor in the head pressure is the change in elevation between the pump and return outlet. Additional impacts on the head pressure include the type and size of tubing and the type of plumbing fittings.

Simplicity Return Pump Family
Simplicity Return Pump Family

Calculating Head Pressure

  • Every vertical foot of distance the water travels equals one foot of head pressure.
  • Every 10 feet of tubing through which the water travels equals one foot of head pressure.
  • Each 90-degree bend adds one foot of head pressure.
  • Use tubing of the same diameter or larger than the pump output to avoid additional head pressure.

General Recommendations

  • Fish-Only Tank: Aim for a return pump with a rated flow of 10-12x the total water volume of your tank.
  • Mixed Reef Tank: Aim for a return pump with a rated flow of 15-20x the total water volume of your tank.
  • SPS Tank: Aim for a return pump with a rated flow of 20-25x the total water volume of your tank.
  • When selecting the appropriately sized return pump, ensure you account for head pressure.


Return pumps are an essential component of keeping any aquarium operating and thriving. Therefore, it is not a piece of equipment you want to skimp on when purchasing. That said, you no longer need to break the bank to obtain one with high-quality. The Simplicity Aquatics DC Pumps come in four different sizes, and each model includes a variable speed controller. Finding a quiet, reliable, and controllable pump can make a massive difference in the environment you create.

General Recommendations

  • Don’t sacrifice cost for quality.
  • Avoid second-hand pumps unless you are buying it from a trusted source.

Final Thoughts on How to Choose a Return Pump

Once you understand the type and size of the return pump you need, you should be ready to make a well-informed purchase. While most high-quality pumps are well built, conducting monthly maintenance by cleaning them will ensure the performance is always up to par.

If you have any questions about selecting the proper return pump, or you need a recommendation, please contact us.

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