By Bob Goemans
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Nano Tanks (written in early 2006)

Authored by: Bob Goemans

During the past few years 'nano' reef tanks, generally aquariums under 30 gallons, have become quite popular. And even if the term 'nano' remains quite correct for all these small aquariums, there's also been interest in what is currently being referred to as 'pico' reef tanks, where I've seen them range in size from a pint to three gallons. No matter what they are called, if my email can be considered a yardstick of their popularity, it has had over the past year a much larger percentage of questions pertaining to these small tanks. Furthermore, the comments noted in most of those letters were that large reef tanks are far too costly or simply too involved to maintain. In some ways I agree, as I've owned many large reef systems over the past thirty years. Therefore I'm quite aware of escalating costs and the associated knowledge needed to properly maintain them. However, if the nano aquarium with its smaller bioload is to be just as fascinating as their larger relatives, then they also are going to require certain expenses and the proper attention to their inhabitants.

So what are the differences besides the obvious such as overall cost, size, and volume of life in the system? Good question, and to help resolve that somewhat, decided to setup a nano system in my office and see where the major differences were, and if the result was just as satisfying.

In my opinion, the first thing to do is resolve its environmental goal, e.g., are you going to want light loving animals or those that will do better under moderate lighting. Then what equipment and general supplies are needed to accomplish it. Keep in mind, the smaller the amount of bulk water, the more careful one has to be in planning and maintaining its bioload! In this case, I decided to set up a small 8 gallon all glass system that would house some corals needing quality light and moderate water movement. That was the easy part and obviously the costs and time involved for doing so where nowhere near what they would be in a much larger system. (Which my signification other was 'very' happy about!) With the tank up and running, I found three areas: temperature control; calcium and alkalinity maintenance; and, the control of phosphate that were far less involved to maintain when compared to larger systems.

Temperature Control

Having a small body of aquarium water can lead to having far greater temperature fluctuations as its easier to affect that small volume with only small air temperature changes in the room. And that applies to both heating and cooling aspects! Both were needed for this small system as my office can get to the mid 60's during winter months, and high 80's during peak summer months here in the mountains of southern Arizona. Where heating was concerned, I found a small heater that was a combination heater and water pump made by Hydor, called the EKIP Thermopump. This one item then provided two services: heating and some water movement. Therefore it was not necessary to put a separate powerhead in the aquarium, which would have detracted from its more natural appearance.

Cooling, as in all my previous large systems, required a standalone chiller to keep system temperature in the proper operating range. Besides costly, they took up a lot of additional space along with involved plumbing connections in some cases. And if one is going to have a nano tank, I would think having something almost as large as the aquarium next to it for cooling would be distracting to say the least. But previous research with CoolWorks Inc., now called Nova Tec Products, showed that they had a product called the 'IceProbe' that could be used in a modified hang-on-tank filter!

IceProbe is a small thermoelectric chiller about 4 inches (10 cm) square, has 1.5 inch (3.5 cm) high main body, with a muffin fan attached to its top surface and a probe extending three inches (7.5 cm) from its lower body. Overall height of the unit is about 7 inches (17.5 cm). The upper portion of the 'probe' is threaded and contains a nylon nut and silicon washer so it can be mounted as you would any bulkhead fitting. If mounting it through the wall of an aquarium or sump, an approximate 1.25 inch (3 cm) hole is needed to accommodate the probe.

Since I didn't want this unit sticking through the side of this small tank, and still needed more water movement than what the heater unit provided, I decided to locater the device in a Hagen AquaClear Power Filter. By cutting a hole in its cover plate, removing the filters media holder and filter medium, the IceProbe's probe fits through its cover and into the empty filter medium space with its probe sitting in the water returning to the aquarium. (See the attached photo) This then provided additional water movement and temperature control. Along with its automatic Proportional Thermoelectric Controller (has a temperature range of 65 to 85 degrees) and its 12 VDC Power Station it was the ideal way to control water temperature, and was set for about 79 degrees. During winter months when cooling is not needed, the IceProbe is removed and the HOT filter's media is reinserted.

This has proved to be an 'ideal' way to resolve both heating and cooling parameters, as the heater comes on about 77 degrees, with the system not getting any cooler than 76, or warmer than 80 degrees.


Another time consuming and often expensive, as additional major equipment may be needed, is controlling the calcium/alkalinity aspect in much larger reef systems. Utilizing a calcium reactor and/or calcium hydroxide stirrer to control this parameter has always been part of my larger systems. But such equipment would be ridiculous for a nano system, and besides, I really didn't want to have any kind of separate stand-alone equipment that would exceed the cost of my nano tank! The simplest and most cost effective way to resolve the maintenance of these parameters was with the use of one of the many two-part calcium and buffer solutions on the market.

Phosphate Control

As in larger systems, phosphate control is an extremely important aspect. If its not controlled, as being kept below 0.015 ppm, unwanted forms of algae may become a costly task to overcome. Therefore, in all my large systems I've always used products such as ROWAphos, Marc Weiss Phosphate + Silicate Magnet, or Two Little Fishies Phosban to mention just a few of them. All worked exceptionally well, yet they were all a powder-like substance, therefore needed, in my opinion, to be used in a separate canister filter.

But again, where this small nano system was concerned, I didn't want to add another piece of equipment, especially something that would come close to equaling the size of the aquarium. So I decided to test two products that were far easier to use, i.e., Boyd ChemiMat filter pads, and a fairly new product by CaribSea called Phos-Buster.

The Boyd product, which consists of two large, very thin pads, was horizontally cut into ten strips. One strip was folded and placed in the top area of the hang-on-tank (HOT) filter. The strip is thrown away about once every month and a new strip is installed. A single one-inch (2.5 cm) wide strip of this double pad was sufficient to keep phosphate at undetectable levels when changed monthly.

As for the CaribSea product, it's a liquid and also found it simple to use and very effective. When I used this product, I tested for phosphate every few weeks and if there were any indication of it, would simply add the recommended number of drops of this liquid and the phosphate disappeared.

And yes, I feed the system quite heavily as I use various zooplankton and phytoplankton additives every other day and in between feed its three gobies meaty foods, although sparingly as there is a myriad of copepods in the aquarium. Both products proved to be ideal for this nano tank and did an excellent job at keeping phosphate at acceptable levels. And besides being easy to use, they were also quite cost effective.

Other Parameters

As important as the three parameters mentioned above are, there are some others worth mentioning. And they should be given some consideration while in the planning stage.

Protein Skimming

In the last twenty years, I've never had a major size aquarium without a protein skimmer, which I consider the aquarist's most valuable tool. It not only reduces the level of nutrients in the aquarium, it also oxygenates the bulk water. Nevertheless, I've kept numerous small aquariums, many of them with a complex grouping of animal life, without skimmers quite successfully. And I've found this small nano reef system no different. To do so simply takes some planning as to what animals will be placed in the system and their nutritional requirements, then self-control so as not to exceed that. However, I've recently seen some new skimmers made especially for nano tanks, and intend to test one soon.


After looking at many different prepackage nano tanks, I decided that their light hood would not provide enough light for the corals of my choice. I also preferred a more open area at the waters surface so as to promote good gas exchange, therefore did not want a nano aquarium with a hood enclosing the entire top of the tank. The Stand-Off fixture (shown in the photo) with two Power Compact 50 watt lamps, each on a separate circuit and a small LED moon light from ARAD Inc., resolved this issue. And with the lamps being about four inches (10 cm) from the water's surface, there's practically no lamp heat transmitted to the aquarium water. For my little system and its corals, the stand-off fixture was the way to go.

Algae Control

We've all probable seen the movies titled 'War of the Worlds!' In aquarium land, the unwanted monsters are 'green' and there's very few aquarists' that hasn't gone to war with unwanted algae growths. Nevertheless, small amounts of algae are a normal part of every ecosystem. The problem is when it gets out of control and begins to interfere with healthy coral growth or becomes unsightly. And honestly, I've had my share of those battles; maybe wars would be a better choice of words, in some past systems. Even though I found my way successfully through those battles, the cost in time and efforts were not pleasant. But now, with a new 100% organic product from Weiss Organics called 'Algae Magic,' it may be possible to bypass those wars, or at least keep them well under control. And since I feed a lot, decided to give this product a try and see where it goes. So far, so good after using it for the past eight months. And should mention, it has no affect on coralline algae, as I'm using a product from CaribSea called 'Purple-Up,' which is beginning to promote major coralline growth.

In closing, I've found my Porites corals needing more water movement, so added another Hagan HOT filter, which makes for a perfect place to add my liquid additives. And the products mentioned above are only some among the many now available on the market that can make nano reef systems very successful. I should also mention the whole system is powered by electricity from sunlight and wind power, as most of my office electrical outlets are powered by these sources.

And finally, yes, my nano tanks are just as satisfying as their much larger relatives.

Nano Do’s

Ideal Fish Species -

Small Gobies, e.g., Eviota spp.; Trimma spp.; Trimmatom spp.






Ideal Invertebrates

Various slow growing soft and stony corals

Snails/Clams/Hermit Crabs/Shrimp (various species)

Small Sea Stars/Brittle Stars, including Featherstars

Sea Squirts/Sponges

Feather Dusters/Co-Co Worms/Christmas Tree Worms

Nano Don’ts (Whales and Sharks - You get the point!)

Some Unsuitable Fish Species













Some Unsuitable Invertebrates

Fast growing soft and stony corals

Urchins (Bulldozers)

Large Sea Stars



Nano Environmental Goals

Mixed environment simulating a small portion of an actual reef

An alga-based system for stimulating micro-crustaceans growth/live food production

Dedicated environment for a very specific animal species, such as pipefish or a featherstar, where its nutrition requirements can easily be met

Breeding/propagation system dedicated to a small specific species.

System dedicated to an aesthetic form of alga, such as the Botryocladia ‘red grapes’

A ‘Cold’ water system

Important Nano Environmental Parameters

Temperature Control (Heating & Cooling)

Water Quality/Water Changes

Water Parameters





Specific Gravity

Water Movement


Evaporation Makeup

Aeration (especially in closed top systems)

The ‘More’ Important Points of Nano Husbandry

Greater qualities of water changes

More attention to water quality, water temperature, and nutrient control

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