Refugiums are a great addition to any saltwater aquarium. They have so many benefits, helping out both you and your marine life. But if you are a beginner, you might be a bit confused about how exactly you might set one up. Don’t worry, we are here to provide a simple guide for you to understand how to set up the perfect refugium. 

Why Use A Refugium? 

Firstly, we need to understand the huge benefits that refugiums provide. It is a mini aquarium that is connected to your main tank and gives you space to maintain marine life that might be at risk in your main aquarium. This might be live feed or little creatures that you enjoy having but get preyed on by bigger fish in the main tank. The refugium basically is a refuge for any marine life that needs it!

Refugiums also provide a filter for the water in your saltwater aquarium. Having one means that there are more water changes going on and this acts as a buffer for the quality of your water. 

Another reason why refugiums are really important as they keep your aquarium clean, without you having to do much! They keep on top of levels of nitrates and phosphorus by locking away the debris that gathers in your tank. This breaks down to nitrates and other matter that is then used by algae in the refugium. This also means that the oxygen levels in your tank can be kept stable. 

How To Set Up The Perfect Refugium 

So, refugiums are great and do so much for your tank. But how do we set up the perfect refugium? 

Before we begin, we have to decide what refugium we want to add. There are three main types of refugiums. 

You could choose to keep the refugium in a sump below your tank. This means that they are connected to the main aquarium and filters the water in and out through the different chambers. This is good because it means there is a higher volume of water in the flow. 

Some hobbyists have their refugium in the tank where it is a small enclosure that keeps bigger marine life out but allows smaller ones and water to flow through. 

You can also have a refugium that hangs off the tank which cycles the water in and out. 

When you have decided what type of refugium you are adding to your tank, you can now work on perfecting your refugium! 


When it comes to setting up the perfect refugium, you have to have the right substrate. It all depends on what you are wanting to keep in your refugium. If your refugium is small with little algae and creatures in, you could get away with no substrate and maybe a few rubble rocks. This makes your refugium super easy to clean.

However, if you are keeping planted macroalgae you need a substrate. The substrate also provides a place for microorganisms to thrive.

Sand is a great substrate for refugiums, and there are also refugium mud substrates available that are designed for the life that is kept in refugiums. 

If you are keeping small creatures in your refugium for safety, such as shrimp or crabs, make sure the substrate you are using is suitable for them. For example, if you are keeping Nassarius Vibex snails, you need to have a sand substrate for them to sift! 


If you have a hang off or in-tank refugium, the lighting from the main tank will suffice. However, if your refugium is in a sump below your tank you need to provide lighting for it. 

Having lighting specifically for your refugium has benefits. It means that you can pick the best lighting for the macroalgae in the refugium to thrive. You can buy lighting that is designed solely for refugium algae growth!

Having separate lighting also means that you can set the system up so that the lighting is on when the light in the main tank is off. This is extremely helpful in balancing the oxygen and co2 in your tank. 

This is because corals will not consume co2 at night and this can lower the pH levels in your tank. Having lighting on in the refugium at night means that your macroalgae will consume the co2 and therefore keeping the right balance in your aquarium. 

Water Flow

The water flow to and from your refugium depends on what you are wishing to keep in it. However, as a general rule, a lively flow is great for keeping the water system fresh and the bacteria moving into the refugium. The water in the refugium should change in about an hour to make sure the system is working properly. 


Macroalgae is super important when wanting to set up the perfect refugium. These soak up nitrates and phosphorates that are harmful to the overall health of your saltwater aquarium. Gracilaria is a macroalga suitable for beginner hobbyists who are creating their first refugium. These plants not only work well in cleaning the tank of nutrients but some fish, like tangs, like to eat it! This means that you can harvest the plant and feed it to your fish when needed. 

We have a huge range of macroalgae available, from the wonderful green spicifera to the aptly named shaving brush plant. A huge choice for your refugium! 


If you really want to get the most out of your refugium, adding marine life is a must. 

Copepods and amphipods can be added to the refugium as they feed off the debris that might be lingering around. If you add these mini crustaceans, be sure to add phytoplankton for them to feed on. 

The refugium gives copepods and amphipods a place to reproduce without being eaten by bigger predators. You then can harvest these crustaceans when ready and put them in the main tank. 

A great addition to your refugium is a small cleanup crew, such as hermit crabs or snails. This provides them with a place to consume the debris and food particles that might be in the water without running the risk of a predator eating them. 

Find What Is Right For You

When it comes to refugiums, practice does make perfect. However, these tips give you a great starting point for creating the best refugium. 

Go ahead and experiment and find out what works for you and your saltwater aquarium! Look at what you need out of a refugium and what you can give it. Once it is set up and settled in, you will wonder why you didn’t add one sooner!