Making Refuge

If you are relatively new to marine tank keeping, you've probably seen the term “refugium.” A refugium is exactly what it sounds like, a place of refuge to grow things where they can't be eaten by aquarium inhabitants. They have many benefits, and can be as simple or as complex as you choose. Why keep a refugium? Let's discuss.

The simplest (and in our opinion, best) way to keep a refugium is to dedicate a chamber of your sump to it. The simplest sump refugium is just a chamber that is full of extra rock, or a super porous media like sintered glass, or Seachem's “Matrix.” Adding this rock will dramatically increase the amount of surface area available for colonizing bacteria, giving your system an amazing boost of nitrogen fighting power. This extra media will even help drop nitrate levels in your aquariums. The crooks and crannies made by the extra rock provides living quarters for beneficial copepods and amphipods in your system. These will get washed into the tank on a regular basis, offering a nutritious live food for your aquarium inhabitants.

The next step up in refugium complexity is to add algae to the chamber. Over the years, many different types of algae have been used in refugia with mixed results. We suggest you use chaetormorpha; usually a few different species are offered, with little to tell them apart to the naked eye. Which one you get really won't matter. Chaeto is a relatively quick growing, stable algae that aquarists have been using for decades now with little downside. Many other algaes are frequently available for sale, but most have downsides as they relate to use in a refugium. Avoid Calupera species of all types, as they have shown to be very invasive if they ever get loose, and also have a tendency to melt inexplicably dumping a huge whack of nutrients back into your aquarium.

Obviously, growing algae means you will need a light. Cheato grows best under relatively high lighting, and you can choose your own lighting for this. Personally, I've had great success using the tile lights available from Aquabeam. Get some Chaetomorpha from your aquarium store, put it in your sump, and place the light above the algae. You'll either want to leave this light on 24 hours a day, or to time it opposite your main display lights; if your tank lights are on from 10am to 8pm, then the refugium lights should be on from 8pm until 10am. Sometimes you'll find that this is too much light for the Chaeto, and if this is the case, you will either need to turn down the intensity of your light, move your light further from the algae, or if these two things do not work, reduce the hours that the light is on.

Having algae in the sump has two important benefits. One is nutrient removal; as the algae grows, it removes phosphorus and nitrogen compounds from the water. You will then harvest this algae and remove a portion of it on a regular basis, thus removing these nutrients from your display permanently. The algae you remove can be composted (in small amounts, remember you don't want too much salt in your compost) or it can be given/sold to other aquarists looking to start their own refugia.

The other important benefit is pH balancing your aquarium. If you take a pH reading of your aquarium you'll notice surprisingly large jump between daytime and night time pH. This is because the critters and algae in your display suck up CO2 and produce O2 during the day via photosynthesis and this process naturally boosts pH. Additionally, an opposite flow occurs in dark conditions, dropping pH. (Photosynthesis is another article). In heavily stocked systems, the resulting pH swing can be more than a full point. Timing a refuge's lighting in opposition to your display lighting naturally combats this swing. As a result of its loose growing structure, Cheatomorpha is another excellent home for copepods.

There are many people who swear by the use of deep sand beds and/or mud in their refugium. At least in the beginning, we suggest sticking with rock/media and/or chaeto, this make up is simple, works well, is easy to implement and clean. A recipe for a good refugium would be to take a couple media bags and fill them with rock rubble, sintered glass balls or Matrix and add these to an unused chamber in your sump. Then add a ball of chaetomorpha and set up your lighting. Lastly, (with the return pump off) add a couple bottles of Nutramar Tigrio, (live copepods) and a bag of Nutramar Live Phyto TC in order to help get the system seeded and add some food for the Tigrio. Turn the return pump back on after 15 to 20 minutes, after giving the copepods and algae time to get down into the rock and algae mix.

As far as maintenance of the refugium goes, the bags of rubble should be dunked in saltwater to rinse off excess detritus every month or so, depending on how much detritus builds up. The bags make this job pretty easy. Alternate which bag you rinse every time you do a water change. Once the Chaetomorpha starts to grow consistently, remove about ¼ of it every month or so, unless it starts to grow very quickly. Never remove much more than the ¼ of it at a time, but more frequent trim downs may be necessary at some point. We also recommend re-seeding the refugium with a mix of the same and or other live algae products from Nutramar on a regular basis. Restocking copepods occasionally never hurts either as excess populations will just wash faster into the main display and become both food and useful parts of your clean up crew there.

As referenced before, there are many ways to implement a refugium, and a ton of nuance that we have glazed over in this article for ease of reading and implementation. This being said, our in-house team has run a wide variety of these systems over time and we all agree than generally, simpler is better. If you follow these simple steps for setting up a refugium, you should see a noticeable drop in nutrient levels and increased stability in your pH levels. In addition, your fish will get a consistent, nutritious food supplement! Head over to your LFS to get some rubble, Chaeto, Nutramar Live Algae, and Live Copepods today! Tell them Quality Marine sent you.