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Reef Aquarium Filters - Using a Refugium Filter

Refugiums For Your Reef Aquarium


The refugium system is my favorite and is the system type I use on all of my reef aquariums. This type of system is based on the sump type system and starts with a separate aquarium that will house all the components and increase overall water volume.

To create a refugium system, you place live rock, a large amount of macro algae, and a deep sand bed inside your sump. The sand bed replaces the need for bio-balls or any other type of biological filtration. The benefits of having a refugium on your aquarium are as follow:

1) The increased water volume will create all of the benefits that were listed in the sump filter section.

2) The removal of bio-balls and the addition of live rock have a two-fold effect… First, do you remember that the bio-balls would release Nitrates back into your aquarium water? Well, eliminating bio-balls will eliminate that potential problem. Second, the addition of live rock creates a bacteria rich environment that will increase the transformation of ammonia to less dangerous compounds.

3) The deep sand bed (at least 6” deep unless you’re using a refugium mud like “miracle mud”) will create a low oxygen environment that is perfect for the growth of nitrifying bacteria. These bacteria remove nitrates from the water and release them as nitrogen gas that is easily transferred to the air without additional equipment. These bacteria only exist in low flow, low oxygen environments and are the only way to remove nitrates from your aquarium without adding some type of chemical based nitrate remover.

Note: It is important that you do not disturb the refugium’s sand bed once your system is set up. When you create a low flow, low oxygen environment, hydrogen sulfide is created. This is a toxic compound that is very dangerous to aquarium inhabitants and it is essential that you do not disrupt it into your aquarium water. It might seem strange to have this type of system when it actually creates a dangerous compound, but when the refugium is established there will be no need to disturb the sand bed. Thus, hydrogen sulfide will never be released into your aquarium.

4) The macro algae that are grown and harvested in the refugium use the phosphate in the water as a fertilizer and, thus, lower your phosphate levels significantly. I had phosphate levels of .2 in my 65 gallon tank before I installed a refugium. Once it was installed, my phosphates were below .02!! When your phosphates are low, coralline algae will flourish, slime algae will die, and everything will be healthier.

5) A refugium must be lit 24 hours a day and, thus, will reduce if not eliminate PH drops at night.

6) A refugium will breed micro algae and copepods which will be pumped into your tank all day every day. The micro algae will feed your corals and the copepods will feed other reef inhabitants, especially Mandarin Gobies!! Even if the copepods get chopped up in the supply pump, their pieces will become healthy food for all of your reef inhabitants.

We recommend you put a refugium on your reef aquarium, period. This filter will complete your nitrogen cycle, stabilize PH fluctuation, reduce phosphate levels, breed beneficial copepods and micro algae all while increasing the volume of your aquarium system.


Chemical Reef Aquarium FiltrationMechanical Reef Aquarium FiltrationBiological Reef Aquarium Filtration

Reef Aquarium Sump Filters

Reef Aquarium Wet-Dry Filters

Reef Aquarium Refugium Filters