What is An Aquarium Sump?

To put it quite simply, the sump is often the heart of the whole aquarium system. Aquarium sumps provide extra space to put any life supporting machinery, mechanical filtration, protein skimmers, media reactors, heaters & dosing pump lines. This allows hobbyists to have all their aquarium equipment out of sight and maintained from one central point.  

Aquarium sumps are usually located below the main aquarium to assist with  various filtration functions and provide some extra water volume. The extra volume helps a little bit with the aquarium's stability in water chemistry and temperature. Sumps can also help with tank hygiene, filtering out impurities and debris from the water.

What is a Refugium?

This is a "refuge" area that typically houses live rocks, various types of macroalgae (desirable species), organisms that help to clean aquarium water and a light in the 6500k spectrum (freshwater plants grow light).

This creates a small ecosystem separate to the main display in which small creatures can thrive. This dedicated environment offers a controlled and separate space to grow organisms that may not thrive in the main aquarium tank or that you simply don’t wish to have on display in your tank.

These refugium tanks are usually placed hanging at the back of the main aquarium, or can be a separate box that can be tucked out of sight or within the aquarium on display itself based on personal preference.

An effective aquarium ecosystem functions, of having this separate refugium means small creatures usually make their way to the display tank via the return pump and become food for corals and fish.

The macro algae uses up undesirable nutrients in the water as it grows and you harvest the excess algae to permanently remove those nutrients.

A well made and maintained refugium is an excellent addition to any reef aquarium.

What’s the main difference between a sump and a refugium?

The main difference between an aquarium sump and a refugium is that a sump is designed to be used within an aquarium system to house filtration, pumps, filter media and other equipment. While a refugium can act as a biological filter system and is used to house things like live rock, sand, and macroalgae. 

In some cases sumps are combined to house refugiums, as they offer another system to harbour another world of life out of the way, and add extra water volume to the system.

Things to Consider when Planning Your Sump

• Make the sump as big as you can

• Allow room for all the equipment that you currently have and plan to have.

• Ensure the sump has enough volume to handle back siphon.

• Allow good access to all of your aquarium equipment

• Think about electrical safety and organising cables properly

• Avoid using metals like steel or low grade stainless steel to minimise rust in the sump.

Other features to consider when setting up your aquarium sumps

Baffles

Glass divisions known as "baffles" are set in place to create each compartment.

A bubble trap is a series of 3 or 4 closely spaced baffles placed right before the return pump.

They direct water over and under them, each time the water is pushed up the micro bubbles created by machines such as the skimmer are left at the surface where they cannot be pulled into the return pump.

There is no huge danger of having these bubbles but they cause the aquarium display to look dirty and they burst on the surface creating salt spray on your lights.