Nano Reef Tank Tips

Follow these reefkeeping tips to increase your likelihood of long-term nano reef aquarium success.

Small cardinalfishes such as these threadfin cardinals (Zoramia Leptacantha) make for a fascinating addition to a nano reef. Just make sure you don't overstock your small tank. Photo by Scott W. Michael.

Nano reef aquariums have many appealing characteristics, and last time we went over some nano-reef basics. At this time, when many people are careful about how they spend their money, nanos are likely to be more widely considered. They are less expensive to acquire, set up and stock, require less energy to maintain and can fit into a more confined space. That said, there are also some inherent risks or potential pitfalls in keeping a smaller aquarium. Here are some things to consider that will increase your likelihood of long-term success.

Regular Maintenance

If you really think about it, much of our lives involve some type of maintenance (I have found this to be especially true since I bought a home and now deal with an older house, a lawn and a landscape). If you buy a saltwater aquarium, be prepared for more maintenance activities – and if you get a nano reef, be ready to do them even more religiously. Because of their smaller water volume, nano-reef aquariums are less forgiving than their larger counterparts. So if you don’t have the time or inclination to do these regular duties (or you don’t want to pay someone to do them for you), you may want to reconsider acquiring a nano reef. For those who are up to the challenge, here are some things to consider.

Tasks that you will need to do daily include replacing water that has evaporated from your system with fresh reverse-osmosis (RO) water, feeding your animals, checking the condition of the aquarium inhabitants and equipment, and removing algae from the viewing panes (this may be done less frequently if microalgae  growth is limited).

It is important to conduct regular water changes at least once a week. Water changes are the easiest way to deal with the build up of bad things (e.g., dissolved organics) and the depletion of good things (e.g., trace elements). One of the great things about a nano reef is it is much easier to do significant water changes because of the aquarium’s smaller volume (e.g., a 10-percent water change of a 10-gallon tank is only 1 gallon). Because we are talking about minimal water volumes, it is easy to have an equal volume of prepared saltwater on hand in case of an emergency.

I use a 30-gallon trash can as a “backup” receptacle complete with a heater – I hang the heater from a plastic rigid tube placed across the middle of the can so that it does not melt the plastic. Take a large (32- or 44-ounce) plastic drink cup and slowly pour the fresh seawater into your nano reef. When you do water changes, remove as much detritus as possible. Use some plastic rigid tubing attached to a flexible hose so that you can vacuum detritus out from between rockwork as you siphon out 10 to 20 percent of the tank’s water (the amount removed will be a function of how heavily the aquarium is stocked).

Also clean any mechanical filters where detritus has had a chance to accumulate at least once a week. Once again, while it is a good practice to do this regularly in any aquarium, it is even more important in an aquarium of smaller volume. Some people rinse mechanical filter media in a bucket with waste water from the aquarium in order to not destroy beneficial bacteria growing on the material. I prefer to rinse it under a high-pressure faucet to remove as much of the accumulated detritus as possible, even though it may destroy some of the beneficial microfauna.

To keep detritus accumulation in check, it is a good idea to instigate a “faux hurricane” at least once a month. Use a small powerhead to blast water jets around the live rock in order to dislodge and remove accumulating detritus (while some of this will be caught by mechanical filter media, you can also use a fine-mesh net to strain floating debris from the water column).
If you are keeping stony corals, keep a close eye on the calcium and alkalinity levels (these levels should be checked on a weekly basis). Faster-growing corals (e.g., Acropora spp.) will rapidly deplete available calcium. As a result, you will have to frequently add a calcium supplement. Ideally, calcium levels should be maintained between 350 and 400 parts per million (ppm), while an alkalinity level of 12 dKH should be your target. A declining pH can also be a problem, but it is less likely to be if you practice good husbandry and if you have an aragonite sandbed. Check pH at least once a month and always test at the same time of day.

One piece of equipment that can keep water quality in check is a protein skimmer (some setups come with a skimmer, and for those that don’t, you can always add one). However, if you are careful not to overstock and overfeed your aquarium, and you do frequent water changes, a protein skimmer is not essential to success. Occasional use of high-quality carbon, as well as phosphate removers, can also be useful. Replace these as suggested by the manufacturer, as they will eventually release pollutants they have pulled from the water back into the tank.

Bioload: Waste and Aggression

While it may seem intuitive, the nano reefkeeper has to consider the bioload limitations of the aquarium when selecting and adding organisms. Most marine aquarists will tell you that no matter what size their aquarium may be, they are often tempted to add just one more organism to an already burgeoning aquarium community. The problem is that the smaller the aquarium, the more quickly you’re going to reach maximum carrying capacity. With a nano reef, you have to also consider the growth potential of your aquarium charges more carefully.
There are several problems that can arise if you end up with too many critters. The most obvious is that too many organisms can lead to a degradation of water quality. A rise in nitrogenous water levels (e.g., ammonia, nitrite) can be lethal to your aquarium inhabitants, and increased dissolved organic compounds and phosphates will result in noxious algae that can overgrow sessile inverts.

A less recognized problem is aggression that may develop not only between fish but also between cnidarians (e.g., anemones, corals). To dissuade their neighbors from getting too close, some stony corals send out stinging tentacles, and certain soft corals exude noxious chemicals. For this reason, be careful when selecting species for the nano reef if you plan on keeping an assortment of cnidarian species. Avoid coral species that are especially “aggressive” in their defense of space (e.g., elegance coral, Catalaphyllia jardinei; hammer coral, Euphyllia ancora; frogspawn coral, Euphyllia divisa; bubble coral, Plerogyra sinuosa) or keep them on their own. If you are interested in keeping aggressive or predatory fish (e.g., frogfishes, scorpionfishes, dottybacks, certain damsels) or destructive crustaceans, create a species aquarium dedicated only to that one animal. While aggressive fish may pick on other fish, they can be kept with certain invertebrates (especially cnidarians), which can make an attractive and interesting display. Likewise, aggressive corals can still be housed with certain fish. If you add a more pugnacious fish or coral into your nano reef, and it causes problems with its neighbors, remove either the culprit or the targets of its aggression. In the case of corals, if you have space, this may simply mean providing a larger buffer space around the tank’s sessile inhabitants.

Preventing Disease

Parasite infestations can be a lethal problem in any aquarium system. But parasite densities will increase at an even greater rate in a smaller tank, which means the aquarium’s inhabitants can be overwhelmed by these pests even more rapidly. I know many hobbyists hate to hear this, but the best way to prevent disease issues in the nano reef is to quarantine, quarantine, quarantine! Yes, the dreaded Q-word! This does not only mean isolating and observing fish before you add them to your nano-display aquarium; it also means doing the same with corals. To give you an example of the problems that can occur with corals, I had a Merulina coral that I added directly to a nano reef. It turned out that the coral had a few tiny aeolid sea slugs that I did not detect before its introduction. The slugs reproduced, the Merulina was munched on, eventually removed and later perished. Fortunately, the dirty little slugs did not like any of the other corals in the tank, and the problem did not spread, but this is not always the case (ask those who love Montipora corals about losing multiple individuals of various species to predatory slugs).

Because you are dealing with smaller animals, you will not need a very big quarantine tank. A 10-gallon quarantine tank is inexpensive to set up and requires little space. If you detect a parasite or disease in your nano reef, it is imperative to act quickly. I prefer to try and remove the infected fish or inverts; I place them in the hospital tank where they can be treated more effectively. Unfortunately, the most effective treatments for fish parasites will kill invertebrates and the beneficial plant material that grows on live rock (e.g., coralline algae). If you have a single fish that is infected, you can sometimes prevent the spread of the parasite if you remove the fish from the display tank immediately. Placing a UV sterilizer on the nano reef can also aid sick fish in fighting off parasite infections, and cleaner shrimp may pick cysts and certain juvenile parasites off of fish tankmates (don’t count on these crustaceans to rid a tank of a severe infestation, though).

Nano-Tank Maintenance Schedule

Temperature Control

Maintain water temperature in the appropriate range (between 74 and 82 degrees Fahrenheit). In most cases, keeping the tank warm enough is not a problem – all one needs is a reliable heater. The temperature issue most often confronted is keeping the water cool enough. This is especially true with aquariums that have lights and all other equipment completely enclosed in a plastic shell. While these systems usually have fans installed in the top to help vent some of the heat from the lighting system, they often cannot keep up with heat energy produced by bulbs and submerged pumps.

Things can get even worse if the aquarium is kept in a warm location in the house (e.g., upstairs, an area subjected to direct sunlight or near a heating vent). There are small chillers (1/15 horsepower, etc.) available for nano systems, but most aquarists are not interested in investing in one. The best way to avoid a heat issue is to select an aquarium system that has an open top and that has the light mounted a distance above. It will also help to set up the aquarium in a cooler location in the home.

Rapid Changes

One of the problems with a smaller volume of water is that changes occur more rapidly. Since most coral reef creatures are used to a stable environment, dramatic alterations can be catastrophic. One practice that the successful nano reefkeeper will always engage in is to observe his or her aquarium daily.

One of the best indicators of the aquarium’s health is the behavior of the tank’s inhabitants. Do the sessile invertebrates look “happy”? For example, are the polyps fully open, or are they contracted? Are they exuding an excessive amount of slime? Are the fish respiring at a “normal” rate, or are they breathing heavily? Are they hiding more than usual, and are they feeding normally? Observing your animals and knowing what a healthy specimen should look like are both essential to warding off problems. This is not only important for the health of the tank – it is also the reason we set the tank up in the first place.

If you detect these changes in behavior, you are likely to have a serious problem that needs immediate attention. Deal with such issues immediately – putting them off for even a few hours can end in catastrophe for your tank. At this point, figure out what the problem is and respond accordingly. First check and make sure that all equipment is plugged in and running correctly. It may seem like a no-brainer, but there have been many occasions in which a pump was accidentally unplugged (e.g., when feeding) or had malfunctioned and was the cause of problem.

The next thing to do is check the water parameters. Check the temperature, the specific gravity and the ammonia level. Look for all the animals, and make sure that a fish or invert has not died behind a rock and is decomposing in the tank. If the ammonia or nitrite levels are high, use the prepared seawater you have on hand to do a larger water change (e.g., 50 percent) immediately. Continue to perform smaller water changes every day for several days. Then continue testing the water for ammonia and nitrite for a week after the last large water change to make sure these levels remain at zero. In many cases, even if you cannot find the source of the trouble, a water change may be all that is required to fix the problem.

In an emergency situation, one item that can save you money and heartache is a battery-powered air pump (I would have a couple on hand and some fresh batteries in case of a power outage). I hope that these considerations will help the potential nano-reef owner better plan for his or her aquarium. Marine aquarium keeping is an amazing hobby, and nano reefs have made the hobby more affordable to a larger group of people. With careful planning and some good maintenance habits, this is a hobby that can give its practitioners years of entertainment and enlightenment. Happy fish watching!

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Fish · Reef Tanks