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Originated from WWM Digital Magazine: Vol. 2, Issue 3, Winter 2011

Related FAQs: Small Marine Set-Up, Small Marine Systems 2, Small Marine Systems 3, Small Marine Systems 4, Small Marine Systems 5, Small Marine Systems 6, Small Marine Systems 7, Small Tanks, Small System Set-Ups 2, Small System Lighting, Small System Filtration, Skimmers for Small Systems, Small System Stocking, Small Marine System Livestocking 2, Small System Maintenance, Maintaining Small Systems 2, Maintaining Small Systems 3, Small System Disease, Tom Walsh Systems, Marine System PlumbingFish-Only Marine Set-ups, Fish-Only Marine Systems 2, FOWLR/Fish and Invertebrate Systems, Reef Systems, Coldwater Systems, Large SystemsBest Marine Set-Up FAQs 1, Best FAQs 2, Marine Set-Up 1, FAQs 2, FAQs 3, FAQs 4FAQs 5, FAQs 6, FAQs 7FAQs 8, FAQs 9, FAQs 10FAQs 11, FAQs 12FAQs 13FAQs 14FAQs 15, FAQs 16FAQs 17FAQs 18FAQs 20FAQs 21FAQs 22, Moving Aquarium SystemsBiotopic presentationsSkimmers for Small Set-ups,

Related Articles: Small Marine Systems, Small Marine Livestocking by Bob Fenner It's a Small World, Pico Tanks, By Kirby Adams, Tom Walsh's Small Reefs, Fish-Only Marine Set-up, FOWLR/Fish and Invertebrate Systems, Reef Systems, Coldwater Systems, Large Systems, Plumbing Marine SystemsRefugiums

What's A Nano Reef?

Nano Reef Systems, 'Don't Call Me Tiny.'

(Sulu, Star Trek III)

by:  Adam Jackson

Gobiodon rivulatus, pic by RMF

Rules and Guidelines; we all live by one set or another and it's no different when it comes to our aquariums. While many of these standards in the hobby contradict each other and at times and cause confusion or controversy, there are however, a few of these standards that are undeniable. One of these guidelines being: 'Tanks with larger volumes are chemically more stable than those of smaller volumes and thus easier to maintain.' Thus we get the 40-gallon rule, as in no marine system should be smaller than 40-gallons in volume. So the logical conclusion is, 'No one would ever start a marine system less than 40 gallons', but you and I know that this is far from the truth. In fact it's quite commonplace to see aquarists with nano tanks (a.k.a. pico marine systems); tanks whose water volume does not exceed 30 gallons are generally placed into this category. It is undeniable that the popularity of nano/pico marine systems has gained momentum in recent years. Consumers have readily accepted them into their homes and offices and marketers have happily provided them with the means to do so. Indeed the nano tank has a following of its own and this is evident with 'ready-made' nano systems and chat forums dedicated solely to the smaller marine systems. However popularity and 'easy' are not synonyms - nanos are not for everyone.

Who has them?

Although it seems the nano reef craze arrived here overnight, this is hardly the case. The idea of small marine systems has been around long before the overwhelming popularity ensued. Ornamental use of the nano system first became popular within the 'veteran' aquarist community. Aquarists who had long term success in larger marine aquaria used the nano tank as a test of discipline. As time passed more and more people began to venture into the realm of small systems. In Japan, for instance, tanks as small as 2 gallons to ¾ of a gallon are on the hot sellers list. Some aquarists only keep nano systems and even more amazing people are choosing nanos as their first aquariums.

The joys and disadvantages of smaller systems.

To be honest it astounds me why anyone would prefer a smaller marine tank than a larger one. Smaller volumes severely limit your livestock options as there are few animals suited to long term life in such a confinement. The margin of error is severely reduced; one missed water change, a slight overfeeding, death of a tank mate, even a day's worth of unchecked evaporation can cause a small system to crash within hours. Overdosing becomes a big concern as well when it comes to supplements such as iodine, pH buffer, calcium and so on. An overdosing of such chemicals can also swiftly bring a nano into disarray. To be quite honest first time aquarists should not attempt nanos and I find it confusing that at times even veteran aquarists suggest nanos as a good starting point in the marine hobby. Granted that nanos can be convenient at initial cost and size, but chances are a novice would be frustrated with the instability and quit before going deeper into the hobby.

Alas nanos are not all bad. They may be the only option when living in confined quarters or when larger tanks are not financially an option (though many of the extravagant nanos I have seen could have easily been set-up as tanks nearly double their size for the same cost). Nanos can also serve as an efficient display for animals that would not be easily viewed or fed in a large display such as Harlequin Shrimp (Hymenocera picta) or Sexy Shrimp (Thor amboinensis). Nanos can also make great remote refugiums for larger systems; whether it be culturing macro algae for Tangs or providing a fish-less habitat for microfauna to procreate (inline refugiums can serve these purposes as well).

'The Trouble with Tribbles''¦'er Nanos that is

While we were all beginners at some point I must admit the large percentage of failed nanos I have observed are maintained by first time aquarists. All too often beginners are sold on the myth that a smaller system will come with less maintenance than a larger system. Ready made Nano systems have attempted to simplify one of marine aquaria's biggest feats, with marketing claims that suggest their product is the only thing necessary for a successful experience. New aquarists arrive home confident that the local dealer has bestowed all the necessary information upon them only to run into trouble and quit the hobby, often within months. I will go as far as to say it is irresponsible to push a nano on a novice while downplaying or even hiding the obvious complications. I urge all those considering nanos to research thoroughly beforehand, whether you be a first-timer or a veteran. Below is a short list of common problems I have observed pertaining to smaller systems:

Overstocking. Keeping a small water volume stable is hard enough, overstocking it is asking for a quick crash. 

Improper Stocking, entirely different from overstocking, but just as dangerous. Sure some animals are small enough to fit in nanos but that does not mean the environment suits them. I'm sad to say I have seen many dragonets sentenced to death in tanks as small as 10 gallons. 

Lack of Research, That should be enough said, but honestly most of the other problems are results of being unprepared. Research the needs of the animals you wish to keep and decide if you can provide the appropriate environment before purchasing livestock.  

Not quarantining New Livestock. Every time you add an animal that is not properly quarantined you are gambling. A quarantine tank may seem like a hassle but in the end it will save you lot of money, time and heartache. 

Ignoring Regular Maintenance. This act is usually not done purposely but unfortunately usually stems from ignorance or lack of research. The most common maintenance ignored in my observation is the water change. Water Changes are of the utmost importance to any aquarium and with the instability of a smaller volume they become even more important. 

Not Practicing Patience. Over-excited beginners usually commit this act.  They begin to stock to fast (usually before the nitrogen cycle is complete) and the tank never stabilizes. 

Not having a Test Kit. When keeping a nano, or any tank for that matter, it is imperative to monitor the water chemistry as often as possible. Whether it is a small drop in pH or elevated nitrate levels, if a problem is detected early it can be corrected before livestock is lost. 

Not utilizing a protein Skimmer. I find it very perplexing that many people discourage the use of protein skimmers on smaller marine tanks. Protein Skimmers are by and large one of the most essential pieces of equipment for maintaining marine aquaria. We already know that nanos are less stable than tanks with larger water volumes, so protein skimmers should be even higher on the priority list for nano owners. 

Insufficient Filtration Methods and lack of water flow. The 'ready-made' nano tanks come to mind with this one. Many lack the filtration turnover rates necessary to maintain a marine aquarium. The lack of water flow allows detritus to accumulate leading to nutrient issues. 

Disease Treatment. This is yet another problem that stems from many of the others already addressed, including lack of research and lack of quarantine. It is inevitable that aquarists will at times have livestock in their care that experience trauma leading to disease or injury. Those that have not taken the proper time to set up a quarantine tank or research on their own will likely attempt to treat their display. This can lead to a number of problems including destroying the beneficial bacteria on any bio-media or live rock that resides within the display. Or possibly the aquarist will treat the tank without using a test kit to monitor the level of medication in the tank and overdose. Needless to say these and other plausible events can lead to quick trouble.

If You're Going to do Something Wrong Do it Wrong Right!

As mentioned earlier there is a buffet of ready made nano marine systems to choose from. To be honest I have had experience with several of the popular brands now and none have been complete in my opinion. Most of them lack in either water movement or lighting and the majority of them omit protein skimmers altogether. That is why if I were to start a nano tank I would prefer to use a stand-alone tank. Doing it this way gives the owner the luxury of choosing each individual piece of equipment.

Choosing a Tank?

As with any marine system surface area is important when choosing the dimensions of a tank. Of the standard tank sizes available, those that can be bought stand alone and not 'ready-made,' I am fond of the following:

15 gallon (standard) 24 x12 x12 inches

20 gallon (long variance) 30 x12 x12 inches

25 gallon (standard) 24 x12 x20

30 gallon (breeder variance) 36 x18 x12 inches 

These tanks are shallow enough to light easily but still large enough to provide decent surface area for aquascaping and livestock.


If you only take one thing away from this article I hope it's the necessity for a protein skimmer. The easiest way to employ one on a smaller system would be one of the hang on varieties. I would also utilize an ample amount of live rock for biological filtration rather than rely on plastic bio-media. Aside from the protein skimmer, simple power filters can be quite useful in additional water movement and serve as auxiliary filtration for running media such as carbon. Should you choose not to use a power filter or still want more water flow, simple powerheads such as maxi-jet are good choices. In the grand scheme of things the volume of the tank should turn over 5 times per hour at a minimum with 10-15 times being even better. While it is not a necessity I would prefer to use pre-cured live rock in a nano as managing the die off from uncured rock in a small system would be unadvisable in my opinion. Should you have the means to cure rock in a quarantine tank, Rubbermaid tub or even a trashcan these to can be viable options. As for substrate, unfortunately a Deep Sand Bed is rather impractical when working with these volumes so a bare-bottom tank or 1 inch or less of sand for aesthetic purposes only is recommended.


Every once and a while two crazes occur at the same time: along with the nano craze, the hobby is also currently engulfed in the highly lit SPS and Tridacnid tank. The two however are not a good combination. Shallow water organisms come from one of the most stable environments on Earth; a nano is not a stable environment! Hanging a 250-watt metal halide unit over a nano is asking for trouble. At the least you would need an auto top off system and fans to keep the aquarium cool. Even with these, overheating is still an issue, so for the novice aquarist I would recommend against this type of lighting scheme. Overall the type of lighting you choose should be a direct reflection of the photosynthetic (zooxanthelle hosting) animals your tank houses. These are the most commonly used lighting types in the nano-reefing hobby at the moment:

Normal Out Fluorescence In a small tank even an N.O. bulb can provide the necessary requirements for a few animals hosting zooxanthelle.  The disadvantage of these bulbs however is their standard long configurations and large sizes preventing low profile efficient reflectors.

Very High Output Fluorescence, these are high output versions of the Normal Fluorescent bulbs, they have great color, good bulb life with similar disadvantages and also produce more heat.

Power Compact Fluorescence The design of the Power Compact Bulb makes it the most common choice for smaller tanks, though LED's (Light Emitting Diodes) may be taking over that role in the near future. The output even allows for the keeping of some of the more shallow water or 'light greedy' creatures. However while the design of the power compact bulb is its biggest advantage its also a huge downfall. Their side by side, 'bent back on itself' alignment causes the bulb to literally heat itself up and thus the bulb life is shorter. Replacement is recommended every 6 to 9 months.  Furthermore, while a large amount of Power Compact 'wattage' can be squeezed into a relatively small area in comparison to other fluorescent bulbs many hobbyists contend that the color spectrums in relation are not as aesthetically pleasing.

T-5 High Output.  Though expensive at initial cost, the bulb life more than makes up for it. Some of these bulbs can last over 2 years without any depreciation in lumen output. Speaking of lumen output, though the wattage of these bulbs tend to be low, the output easily tops that of PC and comes close to rivaling Metal Halides but without the heating issue. If you choose to ignore the above advice about keeping shallow water organisms in nanos I would prefer you use these lights rather than Metal Halides.

Metal Halides. A member of the high intensity discharge family, although their relative size is much smaller than that of fluorescent bulbs and even incandescent, Metal Halides put out a large amount of power and heat.  While metal halides will undoubtedly provide all the necessary light needed for any photosynthetic animal in nano-aquaria, they provide some challenges for new and undisciplined aquarists.  In some applications they simply provide too much light and UV, literally shocking and killing your  organisms.  In other cases they make temperature control difficult, over heating the tank to the point that your animals, literally cook or causing so much evaporation that water chemistry is affected.  Certain precautions and automation such as fan cooling, chillers and freshwater top off need to be taken into account well before this type of lighting system is purchased.

LED (Light-emitting diode).  While many consider this to be new technology, it's been around for practical purposes since the early 1960's.  However in the past decade LED technology has increased multiple folds and that includes it's long awaited inclusion in our hobby.  Many hobbyists are put off by the initial costs of these systems but with some simple math, you may calculate it to be the best long term investment both financially and ecologically.  LED's impart considerably less heat than other lighting methods, meaning devices such as chillers will either be on less or not be necessary at all.  Less heat means less evaporation, which means you're using less water.  Combining that with the fact that LED's use less power overall and have exponentially longer bulb lives than the other methods mentioned, the investment could be a lot easier to swallow.  What this technology means for nanos is the ability to put more power, in a confined area with less worry, and the automation some systems offer allow hobbyists to simulate more realistic lighting patterns of their targeted bio-tope.

Temperature Control

The temperature of an aquarium is a derivative of several factors, including but not limited to: pumps, lighting, ambient room temperature, and event the material the actual tank is made of. Temperature should be stable between 76 to 81 degrees Fahrenheit. To keep the temperature stable you may need fans blowing across the water surface to cool the tank and a heater to heat the tank.

Stocking the Tank

Once again, you need a second tank to quarantine new livestock. Adding them straight to the display is too large a risk. Also keep in mind that livestock cannot be added the same day the tank is set up; allow the tank to go through the nitrogen cycle with the use of live rock - not fish. After the tank has stabilized (4-6 weeks) addition of livestock can take place.

Invertebrates and Coral:

If your nano is to be a reef tank the invertebrates should be the main focus of the tank. I would add the invertebrates first to allow them to adapt to the new environment without fish poking around. Some (there are many more!) inverts and coral that would make good nano reef inhabitants are:

Common Feather Dusters (Sabellastarte sp.)

Scarlet Skunk Cleaner Shrimp (Lysmata amboinensis)

Fire Shrimp (Lysmata debelius)

Sexy Shrimp (Thor amboinensis)

Cerith Snail (Cerithium sp.)

Nassarius Snail (Nassarius sp.)

Mushrooms (Rhodactis sp., Actinodiscus sp., Ricordea sp.)

Colonial Polyps (Zoanthus sp., Pachyclavularia sp.,
Clavularia sp., Palythoa sp., Protopalythoa sp.)

Leather Corals (Sarcopython and Sinularia Genus)**

**Add these with caution as their potential size may warrant fragmentation

Fish Choices

Nanos are best kept without fish but should you choose to keep them here are some good choices:

Blue Neon Goby (Elacatinus oceanops)

Golden Neon Goby (Elactinus sp.)

Clown Goby  (Gobiodon sp.)

Red Head Goby  (Elactinus puncticulatus)

Bi-color Blenny  (Ecsenius Bicolor)

Rear Spot Blenny (Ecsenius stigmatura)

Two Spot Blenny (Ecsenius bimaculatus)

Chromis (Chromis sp.)**

False Percula Clownfish (Amphiprion ocellaris)**

True Percula Clownfish (Amphiprion percula)**

Firefish  (Nemateleotris magnifica)

Hi-Fin Banded Goby (Stonogobiops nematodes)

Six Line Wrasse (Psuedocheilinus hexataenia)**

Royal Gramma (Gramma loreto)**

Bi-color Pseudochromis (Pseudochromis paccagnellae)**

Purple Pseudochromis (Pseudochromis porphyreus)**

**For the slightly Larger Nano Tank (20 gallons or more)


With Nanos, regular maintenance is key in keeping them stable. Water changes of 10 to 15 percent should be performed at least weekly with bi-weekly being optimal. Bi-weekly water testing is also a good idea. Ammonia and nitrites should always be at zero. Nitrate levels of 15 parts per million and less is acceptable though zero is best. pH should also be kept stable between 8.2 and 8.4; you can make this easier my maintaining high calcium levels (300ppm to 450ppm) and proper alkalinity levels between 8 and 12 dKH. Daily emptying of the protein skimmer collection cup is also recommended. Salinity/Specific Gravity should be checked daily as any evaporation at all in a nano tank could cause these to drastically swing. Should you have evaporation you can top off with freshwater: tap water treated with a de-chlorinator, distilled water or even better water from an RO/DI unit. Any freshwater will have to be pH adjusted before addition to the marine tank. Yearly (or more often) cleaning of the pumps is also a good precautionary measure.


Any disease treatment should be carried out in the quarantine tank and not the display. Be sure to identify the disease before medicating as the wrong medication or over medicating can be worse than the actual disease itself. On top of quarantining initially to prevent disease, other things to consider are pristine water conditions and a proper/varied diet.

All Done!

Overall, nanos are tough to care for and traditionally not for beginners, but not impossible. If you still want one, the information above is a good start but by no means should be your only resource. This is intended as a starting source for you to get a wide scope idea of what the needs and preparations are for small marine aquaria. With anything you do,read the fine print and get the details before you jump in. There are lots of other articles and opinions. Gather as much information as possible, and form your own rules and guidelines.

Bibliographies and Further Readings

Fenner, Robert: Small Marine Systems, WWM

Marks, Christopher: Setting up a Nano-Reef, Nano Reef dot com articles

Pro, Steven: An Ounce of Prevention is Worth a Pound of Cure: A Quarantine Tank for Everything, Reef Keeping Magazine, 2004

Borneman, Eric H., Aquarium Corals: Selection, Husbandry and Natural History

Fenner, Robert: The Conscientious Marine Aquarist

Calfo, Anthony: Water Changes/Exchanges, 2005

Calfo, Anthony: Book of Coral Propagation, Volume I

Wet Web Media Frequently Asked Questions re: small set ups: http://www.google.com/custom?q=small+marine+tanks&sitesearch=wetwebmedia.com

And special Thanks to Sabrina F. for all of the encouragement and tips.

Paper re: smaller marine systems  10/19/05 Hi Bob, <Adam> Adam Jackson here. I don't know if Sabrina had mentioned this to you  (as she is with you currently) but after you encouraged her to write an article  on bloaty goldfish (which I enjoyed by the way) she encouraged me to write an article of my own. <Yes... I encourage you to start... a writing habit... very enjoyable, gratifying... and a good way to build on your learning, reputation... what I did...> The article is on smaller marine systems  A.K.A nano reefs.  I understand that you already have an article on  WetWebMedia and may not have use for it but I chose this subject after  watching (in frustration because they ignored my advice) many  friends/ex-clients fail because they chose a nano a as their first tank and  rushed into it. <Good... If you would, I'd like to have you pen a series... the general/survey work you mention, and topics on Nano/Small Reefs... on Set-up, Lighting, Filtration, Stocking, Maintenance...> I just wanted to give my take/observations on why they fail  and what you can do to make one succeed, though would rather not see a beginner  start with anything less than a 40, that seems to be a consensus among many. Its  a little longer than I though it would be but I tried writing it with a beginner  in mind and not assuming that they know anything yet.  I would love to  e-mail it you, get your take on it if you have the time as I know you are quite  busy. Thank you, Adam J <Thank you, BobF>

Small Marine Aquariums
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