Setting Up Your First Nano Reef Tank

When it comes to reef aquariums, bigger is not always better.

Written by
Nano reef tanks can be beautiful additions to your home, when you plan correctly. Photo by Scott W. Michael

I have been keeping nano reefs for many years. In fact, I was into nano reefs before they were cool. This was out of necessity, not because I was some sort of trendsetter. Nano reefs were ideal for keeping the predacious frogfishes that I conducted research on as an undergraduate student. These gluttons do best when housed on their own because they are inclined to dine on their fish neighbors. I would house them in 2- to 20-gallon tanks with a couple pieces of live rock . I also kept nano marine aquariums during my college days because funds and space were limited. I decided a smaller tank was better than no tank at all. These were not elaborate reef tanks, but they consisted of live rock, some macroalgae and a piscivorous resident (i.e., a frogfish). I also kept some more pugnacious species in these tiny tanks, such as dottybacks, and fish I was interested in studying or photographing.

What is a nano reef tank?

A reef aquarium is traditionally defined as a vessel in which invertebrates and fish are housed together. Typically, sessile invertebrates (i.e., corals) have an important place in the reef aquarium – but not always. The nano reef is a fish-invertebrate community aquarium that is less than 20 gallons in capacity; some define the upper limit of the nano reef as 30 gallons. Some hobbyists label tanks of 5 gallons or smaller as pico reefs.

Nanos of the Past

Of course, back when I started keeping these smaller tanks (in the mid-1980s), most traditional saltwater fishkeepers were of the opinion that small aquariums were not stable enough. Less water means less “environmental inertia,” and inevitably a catastrophe would occur. The minimum tank size of a saltwater aquarium back in the early days of my fish store employ was 30 gallons, but more often than not, store employees tried to steer people to the more “stable” 55- or 75-gallon tanks.

In the 1980s, we certainly did not have access to the amazing array of lighting, filtration systems and foam fractionators that the nano reefkeepers have at their disposal today. Now, not only are these products functional, they are also aesthetically appealing. Many of the prepackaged, contemporary nano reefs are “sleek” systems that are self-contained – all the equipment is strategically incorporated in the aquarium so that the system is aesthetically pleasing. In the early days of the nano reef, it was about improvisation – we did the best we could to glom together a system that would work. Our inferior equipment meant that we were more limited in what we could house in these tanks, especially when it came to cnidarians.

The Nano Surge

In the last five years, there has been a surge in interest in these more diminutive reef aquariums. I believe there are two reasons for this: 1) the nano reefs for sale nowadays are much better than before, and 2) the price of a smaller tank is much more doable than a larger reef aquarium.
There are so many acceptable nano-reef packages available now. You can go to most local aquarium stores and purchase a “nano reef in a box.” Unlike many of the “low-end” aquarium packages that were sold to the new hobbyist, many of these nano-reef packages consist of good-quality components that will facilitate your success in the hobby. For the neophyte, being able to go into a store and buy a box that contains most of what you will need to be successful is much less daunting than having to try and piece together an appropriate system.

The second thing that I believe attracts the first-time marine aquarist to the nano setup is the price. Setting up a 75-gallon reef tank with an appropriate stand, filtration, lighting, etc., can cost a small fortune. Then there is the live rock and livestock. Getting a suitable amount of live rock for the average-sized reef tank is another hit in the pocketbook. Stocking a larger tank also requires more money. I have known people who have spent more money on their large reef aquariums than it costs to purchase a good second-hand automobile.

In contrast, you can buy a good nano-reef setup (equipment only) for a much lower price. Nano reefs vary in quality and price, but even the best of the bunch will not approach the price of a modestly equipped, medium-sized (e.g., 75-gallon) marine aquarium. A smaller tank will also require less live rock and livestock. With less disposable income due to economic woes, more people are attracted to these less-expensive nano reefs.

Selecting a Prepackaged System

Not all nano reefs are created equal. While you can have success with any system on the market (some of these tanks need more modifications than others), some make keeping animals healthy much easier. Many of these systems are like plastic incubators; they have a lid with a built-in light and fan that closes over the aquarium and filter, which keeps condensation and heat in the tank. While this design has its advantages, I have found that these systems are often difficult to keep cool, especially during the warmer summer months.

The open-topped systems that have a lamp mounted on a bracket over the tank work well for temperature control and gas exchange. The biggest downside with the open systems is keeping fish in that are prone to jumping out of the tank.

Another problem I have found with some of the predesigned nano systems is that they are not effective when it comes to surface-skimming. In some of these systems, remove some prefilter media, which tends to impede water flow through the filtration chambers, to encourage better surface-skimming. Of course, if you do this, the water is exposed to less mechanical filtration during the filtering process. Remember that in order to have proper surface-skimming, there has to be a disparity between the water level in the tank and in the rear filtration units. At least some of these systems have an adjustable overflow gate so that you can create this disparity.

Many of the systems available on the market do not include a protein skimmer. A skimmer can help increase your likelihood of success but is not imperative to keeping a nice nano. If you don’t have a skimmer, do frequent water changes (I recommend 10 to 20 percent every week). This is easy because of the small volume of the display tank. To facilitate water changes, I keep a 30-gallon trash can with fresh homemade “seawater” (freshwater with a sea-salt mix added) at all times. It also has a heater (so the temperature is the same as my nano reef) and a powerhead to keep the water well-circulated. If you think you need to foam fractionate, there are small skimmers specifically made for nano systems. At least one system on the market utilizes a mud refugium (small trays of fine substrate in which you can grow macroalgae). Mud refugiums will help keep nitrogenous wastes in check and allow you to add more livestock without overloading the biological filter. Remember that you don’t have to buy a prepackaged nano reef. I have had great luck with nano reefs I pieced together myself (e.g., a simple 5-gallon tank with an external power filter and a good light source). Before you select a system, do your research.

Nano Considerations

There are things to consider before selecting a prepackaged nano reef or putting a nano reef together yourself. Here are some specific things you need to investigate.

Surface Area

It can be more difficult achieving good water circulation in taller aquariums (though less so in a nano than a larger reef aquarium). Also, a taller tank can be more difficult to aquascape and have less utility when housing benthic animals. For example, a 15 gallon (24-by-12-by-12 inches, which is 288 square inches) is going to supply room for more shrimp gobies than the 15 high (20-by-10.5-by-18 inches, which is 210 square inches). There are a number of other standard tanks that can be used as nano tanks that have “regular” and “high” versions.

Lighting Systems

If you are keeping zooxanthellae-dependent invertebrates, you will need an adequate light source. It may be difficult to supply the illumination levels needed by some of the more light-dependent organisms (e.g., tridacnid clams) in the smallest of nano reefs. These invertebrates need the more high-intensity light afforded by a metal halide lighting unit. That said, there are plenty of zooxanthellae-bearing sessile invertebrates that will do fine under the power compact lights found on many of the prepackaged nano reefs.

Temperature Regulation

If you purchase one of the enclosed pre-packaged systems, there will need to be some sort of functional fan in the hood. The lighting system, as well as the pumps in the system, will create heat that is difficult to dissipate in these contained systems. I have heard of small nano reefs that fluctuated as much as 8 degrees Fahrenheit in one day. This type of change is unacceptable in a tank housing animals that are not used to such fluctuations (there are some intertidal species that can withstand these temperature fluctuations).

Many of these closed systems have a fan in the aquarium cover that draws cooler room air under the cover and pushes out air warmed by the lights. That said, they often have a hard time keeping temperatures in check, especially if the ambient room temperature is high. Keeping the small feeding lid open may facilitate some temperature regulation, but this rarely makes a big difference. If it is an open-topped tank, you can place a fan next to the aquarium and direct the air over the water’s surface. This method can drop water temperature significantly (as much as 5 degrees Fahrenheit). It will, however, increase evaporation rates, so be prepared to top off the tank daily. One of the best ways to cool the water is with a chiller. In the winter, in cooler climates, a small heater may also be needed to keep the water temperature in the desired range.

Water Movement

Sessile invertebrates require water flow to provide oxygen, and to get rid of carbon dioxide and slime that they produce. Some species of corals and their relatives require more water movement than others, so do your research. It is essential that you make sure there is enough water movement for the animals you intend to house. This is typically achieved with a water pump that returns water from the sump to the display tank, and small powerheads and circulation pumps that are introduced to the tank. The downside of these pumps is they produce heat and can distract from the aesthetics of the tank. I have found that when keeping corals that do best in more turbulent conditions, one or two additional powerheads (along with the return pump in the aquarium filter) may be needed in a tank as small as 14 gallons to ensure good coral health.

Aquarium Placement

Finally, place your nano reef on a stand, table, desk, etc., that can withstand the weight of the aquarium. Because of their smaller size, these tanks are inherently lighter than their larger counterparts. Still, it is important to make sure that the structure on which your nano tank sits is strong enough to support it. Also, consider the consequences if a seam on the tank splits or the system leaks. Do you really want it to share a desk with your expensive mega-gaming computer? This is something to think about. Also take into account that while natural light can allow zooxanthellae to photosynthesize, it can help heat up a smaller aquarium.

While they require a little extra attention, nano reefs can make spectacular captive oceans. Happy fish-watching!

To ensure success with your nano reef aquarium, be sure to read Scott’s Tips for Nano Reef Success.

Article Categories:
Fish · Reef Tanks