What is a Sump and How To Build One

What is a Sump and How To Build One

Let’s talk about aquarium sumps! What it is, what your options are and how to build one yourself.

What Is A Sump?

A sump can serve a different purpose for people in the aquarium hobby and can also differ greatly depending on what type of aquarium you have, eg. freshwater, marine or reef tank.

In short, a sump is mainly used for filtration and is a place to keep and run all your equipment to keep the main display aquarium clean and free of any equipment inside of the tank itself. A sump is typically a glass or acrylic aquarium with dividers inside. It usually consists of an inlet for the drain from the aquarium, then has a divider with several more compartments for equipment, filtration, etc. and then has a last chamber with a return pump which pumps the water back into the aquarium.

Possible equipment that goes into a sump can be filter socks at the inlet; a skimmer for reef/marine aquariums; reactors such as nitrate reactor, calcium reactor, etc; heaters to heat up the water before going back to the aquarium; rock/rubble/substrate for biological filtration; a refugium with algae or other media to process nutrients; return pump for pumping water back to the aquarium and much more.

Recommended Sump Size

Choosing the right size sump for your aquarium is important.

There can be many debates about this topic but we have a simple rule. Your sump needs to be at least a 1:4 ratio compared to your main aquarium and anything above that. So if your aquarium is 100 liters, your sump needs to be at least 25 liters or more.

The bigger the sump, the better! It increases water volume and provides more space for filtration media and equipment.


Sump Options

There are several options when it comes to sumps for an aquarium. Here is a quick summary:

  • Purchase a premade sump, ready for use.
  • Have a custom sump made for you by someone.
  • Build your own sump using a tank, dividers, etc.

We sell the Reef Octopus acrylic sump which is ready to be used immediately. We also sell the Reef Octopus sump partitions additionally so that you can create compartments in the sump as needed.

A custom built sump may be the most expensive option while a premade sump may have limitations and not fully meet your requirements based on what you want to do. If you are up for the project, best is to build the sump yourself. We recommend using glass instead of acrylic, simply because a glass to glass bond is much stronger than an acrylic to glass/acrylic bond using silicone.

How To Build Your Own Sump


To build your own sump, you’ll mainly need a tank and dividers.
You can start with a breeder tank/aquarium and cut glass panels to use as dividers inside.

Here are some videos on how to make a sump:

BRS 160, Week 3: Sumps

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