How to Choose an Aquarium Sump

How to Choose an Aquarium Sump

Once you select an aquarium, it is crucial to identify the filtration needs of your system. The most common and effective way to filter aquariums bigger than 40 gallons is to run a sump. Deploying a sump provides more options and greater customization of the tank’s filtration system. This article will give you all the information you need to choose the perfect sump.

What is an Aquarium Sump?

Display Aquarium & Sump
Display Aquarium & Sump

An aquarium sump is an additional tank that houses extra water and the system’s filtration equipment. Sumps are placed below the display aquarium and provide the space for different types of mechanical, chemical, and biological filtration.

Benefits of an Aquarium Sump

One of the most significant benefits of a sump is that it provides the additional space needed for the filtration equipment. A sump also allows for many different types of filtration. Another advantage of a sump is that it substantially increases your system’s water volume. This additional water volume helps stabilize water parameters and makes them less prone to rapid fluctuations. Finally, using a sump allows you to hide all of the filtration equipment within it so that it won’t take away from the appearance of your display.

Components of an Aquarium Sump

Aquarium Sump Components
Aquarium Sump Components

Sumps can come in many different variations; however, almost all sumps include an input section, the main filtration section, and a return section. Water drains into the sump in the input section, generally passing through a filter sock for particulate removal. After the input section, water continues into the main filtration section, which houses the protein skimmer in most cases. Finally, water enters the return section before returning up to the display. Other common components found in more sophisticated sumps include a refugium section and a water top-off section.


The most common solution is to put the sump inside the cabinet or stand underneath the aquarium. This allows you to maximize space and keep your system fully contained in the stand. If placing the sump in the cabinet is not an option, putting the sump behind the aquarium is the next best choice. A location behind the tank still conceals the sump, and it shouldn’t have much impact on the head pressure of the return pump. The final option is placing the sump in the basement below the tank. This option requires a powerful pump capable of handling the high head pressure.
Need help estimating the head pressure on a pump? Please check out this article.

General Recommendations

  • Preferred Location: For the majority of installation, placing the sump directly below the tank is the preferred option.
  • Return Pump: If you need to place your sump elsewhere, ensure your pump has enough output to handle the additional head pressure.

Selecting a Size

Simplicity Sump Sizes
Simplicity Sump Sizes

Generally, we recommend a sump is a minimum of 25% of the volume of the display aquarium. We recommend a sump volume of around 35% of the display for mixed reef and SPS dominant aquariums. If you have already purchased a protein skimmer or return pump, be sure that the sump you choose can handle the dimensions of these accessories.

General Recommendations

  • Minimum Size: A sump should be at least 25% of the water volume of the display tank. For an SPS dominant tank, a sump should be 35% of the water volume of the display tank.
  • Plan it Out: Make sure the sump can fit the skimmer and the return pump you’d like to use. Also, save enough space in the stand for components, like dosing equipment and water top-offs that don’t typically live inside the sump.


Aquarium Budgeting

While it may be nice to have a fully customized sump in your aquariums cabinet, it certainly isn’t required to have a successful aquarium of any kind. There are many solutions for creating a sump that doesn’t break the bank. One of the most common ways to create an inexpensive sump is to make one out of a standard glass tank. If you’re interested in building your sump, check out this video from The King of DIY. The final consideration for sourcing an affordable sump is to track down a pre-owned sump; however, make sure it is in good condition and doesn’t have any signs of cracks or leaks. If you’d prefer a new sump, look for a simple design with just an input section, a filtration section, and a return section.

General Recommendations

  • Build your own or look for a quality second-hand sump.

Final Thoughts on How to Choose a Sump

Now that you have selected the proper sump for your tank’s needs, you are well on your way to building a system capable of achieving your goals. Check back for additional parts of our “How to Choose” series for valuable information on return pumps, protein skimmers, and other aquarium equipment.

If you have any particular questions or are interested in a specific recommendation for your space, please contact our customer support team.

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