DIY Aquarium Refugium Design

Design your own refugium to add water capacity and storage to your main tank.

Refugiums are valuable additions to freshwater and saltwater fish tanks. As secondary tanks that share filtration and water circulation with the main tank, refugiums add to a tank's water capacity, making it easier to maintain clean water. Refugiums can also be hidden storage areas or literal refuges for animals that wouldn't survive in the main tank.

Things You'll Need

• Secondary tank
• Power drill
• Plastic hose (two even lengths)
• Sealant
• Substrate
• Water

Instructions

1. Empty the main tank of water and decide on your set up. Your refugium should sit right next to the main tank, but can be behind, beside or below it. Have plenty of room for both tanks; they should be close enough to allow the hoses to reach between them without stretching or kinking. A refugium that's going to be used for fish should sit beside or below the main tank, so that it can be supervised. A refugium that's going to be used to store equipment should sit hidden behind the main tank, to keep the area neat and clean. Deciding on the setup now will keep you from having to move it around later, when your tanks are already attached and have water in them.

2. Remove the filter and pump system out of the main tank and clean them, then set them to the side. This is the ideal opportunity to check the pump and filter for efficiency and to replace any pieces that aren't working.

3. Design your refugium. Put substrate, plants, rocks and other decorations into the refugium tank if you're going to be using it for fish. If you're going to use it as storage for hoses and the filtration system, this is unecessary.

4. Drill two holes in your main tank, toward the bottom of one side or the back. The position of the holes should depend on the position of the refugium; the hoses need to be able to easily reach both tanks. Drill holes that are slightly larger than your plastic hosing, so that you can insert the hoses into the holes. Once the hoses are firmly inserted, use sealant to seal and secure the hoses.

5. Put the pump and filter system in your refugium, where they will now be housed. Attach one hose to the pumping function of your pump, and the other hose to the sucking function of the setup. The pump will now suck water from the main tank, push it through the filter and pump the water back into the main tank. Do not turn the pump and filter on yet.

6. Fill both tanks with treated, fish-safe water. Once the tanks are filled, turn on the pump and filter so that water is circulated between the tanks. Monitor the setup for at least an hour, to watch for any leaks or flooding. This time also allows dust from the construction to settle and be filtered out. After an hour, put your fish back in their tank.

Tips & Warnings

• Use an old fish tank as an easy refugium.

• Use your refugium to safely raise any fish that are born in the main tank.

• Refugiums can overflow if there is a blockage in the hoses. Always monitor the two tanks for even water circulation.

References

• Melev's Reef: How Does a Sump Work?
• Brett's Reef: How a Saltwater Aquarium Sump Works
• Rate My Fishtank: What Is a Refugium