Pet Keen is reader-supported. When you buy via links on our site, we may earn an affiliate commission at no cost to you. Learn more.

Home > Fish > 8 Benefits of Having Freshwater Refugium Filters

8 Benefits of Having Freshwater Refugium Filters

beautiful planted tropical freshwater aquarium with filter

The chances are that if you’re new to the hobby, you’re not ˙familiar with the term refugium. Refugium is defined as “an area where special environmental circumstances have enabled a species or a community of species to survive after extinction in surrounding areas.” The aquarium world describes it as a place apart from the main tank that uses the same filtered water. You can think of it as a refuge for some aquatic species. However, it also offers other advantages for improved water quality. It’s a versatile tool that can solve many aquarium issues.

Three types of refugium exist, each with its pros and cons. You can place a separate container within your tank to serve several of these functions. You can also hang an extra refugium on the back of your aquarium. Finally, you can set up a separate sump underneath it, often hidden from view in a cabinet. Let’s dive into what you can do with a refugium.

pets 6

The 8 Benefits of Having Freshwater Refugium Filters for Goldfish Tanks & Other Aquariums

1. A Place for Live Plants

Live plants benefit any aquarium because they will use the nitrates in the water that are a product of the nitrogen cycle. In addition, beneficial bacteria convert ammonia from fish waste to plant food. You can remove nitrates with regular water changes, or live plants can do the job. However, many fish, such as cichlids and goldfish, are hard on plants.

Using a refugium that isolates plants from these fish can allow you to benefit from having live plants without risking damage. Using up the excess nitrates can also prevent algae growth. It’s an aquatic win-win.

variegated anubias plant in aquarium
Image Credit: Pavaphon Supanantananont, Shutterstock

2. Safe Space for Fry

If you have live-bearing fish, like guppies, you know that you either have to act quickly and get them out of the tank or lose them. A refugium solves that problem with a safe haven for the little ones. The best thing about it is that you’ll minimize the stress of moving the fish. The water conditions are the same, making it the smoothest transition possible.

3. Temporary Housing for New Fish

Joining a community tank is hard for some fish. The stress of leaving its home is complex and can increase the risk of disease. Having a refugium can give your new additions a quiet place to get used to things before turning them loose on the rest of the tank. You may find that the fish handle the change in the environment a lot better.

two fish in a fish tank
Image Credits: cuncon, Pixabay

4. All Aquarium Set-Ups

You can set up a refugium no matter what kind of tank you have, whether it’s freshwater, saltwater, or brackish. They all use the same water, filtered by the same system. You can think of it as an extension of your existing aquarium. You don’t have to get a separate system to maintain the water, either.

If you're new to the world of goldfish keeping or are experienced but love to learn more, we highly recommend you check out the best-selling book, The Truth About Goldfish, on Amazon.The Truth About Goldfish New Edition

From diagnosing illnesses and providing correct treatments to proper nutrition, tank maintenance and water quality advice, this book will help you to ensure your goldfish are happy and to be the best goldfish keeper you can be.

5. Storage for Live Food

Many hobbyists like to offer live food to their fish because they’re often more likely to eat it than frozen or freeze-dried food products. A refugium provides the perfect solution with a place to store shrimp or other live copepods between feedings. It’s helpful if you want to grow them to a specific size before giving them to your fish.

low tech aquarium plants_Amuljar_Pixabay
Image Credit: Amuljar, Pixabay

6. Potential Water Volume Increase

A hanging refugium or sump can add to your tank’s water volume. That can mean more stable conditions and less maintenance. A larger volume is less susceptible to fluctuating conditions. That will mean less stress for your fish. A sump can house your filtration system and heater to free up more room in the main display tank.

7. Improved Water Chemistry

This benefit ties into the previous one. A larger water volume will lessen the concentration of harmful chemicals, such as ammonia. It can also stabilize the essential water parameters like pH. The added surface area of separate refugium can provide more space for gas exchanges and improve the overall quality of the water.

Carassius auratus Goldfish
Image Credit: gunungkawi, Shutterstock

8. Aesthetically Pleasing

We already mentioned the potential water increase. The flip side of that benefit is creating a more attractive display in your tank without the tubes and other paraphernalia taking up space. You can create a more natural-looking environment for your fish, undoubtedly benefiting them. You’ll likely find that you enjoy your aquarium even more and improve your well-being.

pets 6

Refugium Tips

It’s essential to plan ahead if you want a refugium, preferably before setting up your tank. If you’re getting an external one, you need to take into account the extra space required. That applies to a product hanging in the back of the aquarium or a cabinet to hide a sump underneath it. Lighting also becomes an issue with these types if you want live fish or plants in either one.

An internal refugium is the least expensive option. However, it’s also the least visually appealing. External ones solve that problem but will add to your costs. We suggest thinking about how you’d plan to use a refugium to determine the best choice for you.

pets 6


A refugium offers a solution for many issues that hobbyists face with their tanks. Having a separate space in your tank will allow you to keep species that you might not otherwise be able to have with your current fish community. It also offers several benefits for your pets and you. It’s worth considering if you’d like to explore an effective way to improve your aquarium’s water quality or aesthetics.

Featured Image Credit: M-Production, Shutterstock

Our vets

Want to talk to a vet online?

Whether you have concerns about your dog, cat, or other pet, trained vets have the answers!

Our vets