Best Reef Nano Tanks

When it comes to iconic settings, saltwater aquariums are king of the aquatic world. However, starting a large marine or reef tank can be an expensive investment and requires a lot of space and equipment. If you’re pressed for room or prefer to start on a smaller scale, check out the best nano reef tanks!

Quick Comparisons of the 6 Best Nano Reef Tanks

Coralife LED BioCube Capacity: 16 gallons
Dimensions: 17.5 x 16.5 x 15 inches
Features: Glass tank, built-in hinged hood, LED light with self-timer and actinic moonlight, compact internal filter with customizable chambers, submersible pump with dual inlet nozzles
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Fluval Evo XII Marine Aquarium Kit Capacity: 13.5 gallons
Dimensions: 23.4 x 13.5 x 15.6 inches
Features: Glass tank, built-in hood, 3-stage internal filter with additional media compartments, integrated LED moonlight, submersible pump with adjustable nozzle
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Marineland Contour Aquarium Kit Capacity: 3 gallons
Dimensions: 12.05 x 11.82 x 11.62 inches
Features: Glass tank and lid, 3-stage filtration system, Compact LED track light with blue moonlight
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Fluval flex aquarium kit Capacity: 15 gallons
Dimensions: 16 x 15 x 15 inches
Features: Curved glass tank, integrated hood, remote controlled LED light, 3-stage internal filter, dual adjustable outlet nozzles
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Red Sea MAX NANO Rimless Aquarium Capacity: 20 gallons total (16.5 gallon tank + 3.5 gallon sump)
Dimensions: 18 x 18 x 18 inches
Features: Glass bucket tank, rear sump filter, surface and protein skimmers, 3-stage internal filter WiFi-enabled, advanced LED light with adjustable color channels, automatic water fill system
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Marine LED Aquarium Kit Capacity: 20 gallons
Dimensions: 24 x 12 x 16.5 inches
Features: rectangular glass tank, hood with built-in LED light, clip-on HOB filter
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Mini Reef Tanks Guide

There was a time when it didn’t make sense to keep small marine aquariums, due to the immense start-up costs and difficulties in finding specialized saltwater equipment for small tanks. Advances in technology have solved those problems, and there has never been a better time to start a miniature reef aquarium!

Nano tanks are not only suitable for Betta fish and other small freshwater species such as tetras, snails and shrimp. Modern kits make things easy by selling small coral tanks along with the filtration and lighting systems you need to build a thriving ecosystem. Let’s take a look at what you can expect when looking for saltwater nano tanks.

What is a Nano Reef Tank and how does it work?

The exact definition of «nano» tanks varies around the world and has become something of a buzzword in the last decade. So what are nano aquariums and reef tanks specifically?

  • In the US, Nano generally refers to a tank with less than 30 gallons of water capacity.
  • Nano generally describes a tank that is small enough to sit on a table or shelf, as opposed to a setup that requires its own special stand.
  • A nano reef tank is simply a miniature saltwater tank focused on keeping corals, live rocks and sand, and perhaps some small reef fish as well.

You can buy a small aquarium and set up your nano reef system by purchasing each piece of equipment separately, but it is often more cost effective to get a kit. So you can get your tank, filter, and lighting system in one shot!

Types of Small Reef Tanks

There are two types of nano tanks that you will typically see advertised as being appropriate for marine environments. The main difference between the types is their size and water capacity, which determines the type of marine animals you can keep in your tank.

Nano Reef Tanks

If you want the option of keeping saltwater fish along with live corals and rocks, you’ll probably be happier with a larger nano reef tank. Nano reef tanks typically range from 6 to 30 gallons in capacity and come in a wide variety of shapes and styles. This is the best size to start with if you are new to saltwater aquariums.

Peak Reef Tanks

Pico (or Picco, as they are sometimes called) reef tanks are smaller than nano tanks and usually register 5 gallons or less. This makes them the ideal capacity for a desk, bookshelf, or bedroom tank, but also reduces the number and type of reef occupants you can have in them. They are usually suitable for corals but not for fish.

Benefits and disadvantages of the installation of small aquatic reefs

There are several advantages to having a nano or spike reef tank over a 50 gallon or larger saltwater aquarium.

Their main advantage is that they cost less to set up and are easy to incorporate into almost any home or office. Large reef tanks typically require expensive and extensive setups that include multiple external filters, aquarium sump filters, and internal and external lighting systems to highlight the full depth of the tank.

The main disadvantage of small aquariums is that they are more difficult to maintain than larger systems because the parameters and quality of the water can change very quickly. If you miss a water change in your little tank, you could crash without warning. You will also have much less choice in the types of corals and fish you can keep.

Small reef tank type Benefits Corals and appropriate fish Disadvantages
Nano Tank
(6 to 30 gallons)
Ideal type for a starter tank or those new to saltwater aquariums Easier to maintain and less likely to suddenly crash than a smaller Pico tank Not as expensive to start up as a large saltwater tank Compact size makes that is easy to incorporate into your home or relocate if you need to move it You can buy a nano tank kit or home kit and design your own setup Coral: Small, easy fragments of SPS, fungus and soft coral on a base of live rock and sand. Reef fish: clownfish, small varieties of goby, red fishermen, fire fish, and small wrasses such as the pygmy or banded More difficult to maintain than larger reef tanks and more likely to crash due to ammonia spikes Daily to weekly top-ups and water changes required, along with close attention to overall water quality Smaller size limits the type and amount of reef fish and coral you can store Size restrictions also limit your hardscape options, as you need to make room for your fish and corals
Peak Tank
(5 gallons or less)
Ideal size and weight for a desktop, office, or shelf reef tank Less expensive to start than a full-size reef tank Easy-to-find kits that include a filter and light fixture Compact size and lighter weight make it easy to move and relocate the tank anytime you want Coral: Zoanthids, mushrooms, and easy small soft coral fragments on a base of live rock and sand. Reef Fish – Most marine fish are not suitable for such small tanks, but you may have room for a small Goby. Most difficult type of reef tank to maintain Daily to weekly top-ups and water changes required; Close attention to salinity and water quality is required to avoid ammonia spikes and shocks. Not ideal for less experienced saltwater fish keepers Harder to obtain high quality multi-stage filters for Peak size tanks Extremely limited in the types of corals you can keep, and very few fish are suitable.

What Features To Look For In Micro Reef Tanks

Once you’ve decided to start your nano reef aquarium, it’s time to talk about choosing the best tank for your needs. There are a few key factors to consider when choosing a nano or pico tank, including:

Should you go for a Nano Reef kit or build your own tank?

It’s a lot of fun to design an aquarium and choose your own tank, filtration systems, and lighting (more on that below), but it’s harder to do this for mini setups than it is for large marine tanks.

  • There simply aren’t as many choices in high-quality micro tank equipment compared to its full-size cousins.
  • It can be a challenge to find the gear you like that will also fit inside your small tank, especially non-standard or custom sized and shaped tanks.
  • It can also be much more expensive to buy the kit piecemeal than to go with a nano marine kit.

I recommend that novice reefers go with a nano reef kit rather than designing their own small tank as they make initial setup easier and less stressful. Look for a kit in the size and shape of tank you prefer, and one that includes a multi-stage filtration system and robust coral-appropriate lighting.

Shape and size of the nano aquarium

Both types of mini aquariums are available in a variety of shapes and styles, including arched and curved fronts, cornerless, rimless, and cube-shaped reef tanks. However, you will likely find more options for nano tanks than the smaller spike types. Or you can go for a standard rectangular shaped aquarium for your small reef.

The shape of your reef tank is important, because light does not penetrate far into the water. If you opt for a tall style tank, you may be limited to keeping the coral at the top of the tank where the light is ideal for photosynthesis. Shallow tanks may leave more room for corals, but they are not as compact as buckets and bowheads.

Filtration for small tanks

Reef tanks require very high quality filtration systems because corals and many saltwater fish are very sensitive to water quality. A small change in water parameters could easily cause a coral tank to collapse, so don’t skimp on your filtration system.

  • The 3-stage filter with at least one biofiltration stage and room to hold filter media is ideal for reef tanks.
  • Aquarium sump filters are highly desirable for maintaining water quality in coral tanks, which is why the best marine nano tanks include a sump stage.
  • Media such as carbon can neutralize toxins and clean the water, and bacteria in the biofilter and sump consume ammonia and help keep the water chemistry stable.

The shape and style of your tank also affect the type of filtration you can use with it. Cascade filters, for example, often won’t fit in rimless tanks. Nano reef kits typically come with a built-in filtration system that you can modify, making them easier to handle and more compact than a custom setup.

Importance of lighting in reef tanks

Corals are photosynthetic organisms that require a very specific light spectrum and intensity, and the ideal setting depends on the type of corals you are keeping and how far away they are from the light source.

I cover this in detail in my reef lighting article, but the good news is that nano reef aquariums are so small that it’s not hard to find lights for them at a reasonable price. It’s also not hard to find reasonably priced compact LEDs to modify or upgrade your reef tank kit if the included accessory doesn’t make the cut.

Many compact LED lights produce the right spectra for growing the easier types of soft corals and SPS (small stony polyps), and most marine nano tank kits come with the right lights to support a basic reef environment. If you are purchasing your light fixture separately, you will need to research the best system for your particular tank.

How to set up a reef tank

The initial setup of a reef tank is similar to that of a freshwater aquarium:

  • Unpack your equipment.
  • Rinse your substrate with salt water or use live sand packed in salt water and place it in your tank.
  • Set up your filter, heater, and lighting system. Then you can fill your tank with salt water and start cycling your new reef tank!

Cycling your reef tank

You can add live rock to build the base of your reef as you go through the tank, but you should not add any corals or fish for at least 3 to 6 weeks. It takes time to establish the good ammonia-eating bacteria, and your tank may spike and block as the nitrogen cycle establishes itself. Limit your light levels to reduce algae growth.

Establish your maintenance routines

You will need to fill your tank with water and check the pH and salinity at least several times a week and possibly as often as daily. Maintaining a saltwater aquarium is much more labor intensive than most freshwater setups, so develop a good routine while cycling your tank to make things easier once you add corals!

Add Coral and Fish to a Reef Tank

Once your tank is cycled and the pH, salinity and hardness of the water are stable, you can slowly begin adding coral fragments and fish to your reef environment. Once you have a thriving population of animals in your tank, you’ll need to start with regular water changes and adjust your day and night light cycles to maintain your corals.

Best Small Reef Aquariums: Nano Kit Reviews

Let’s take a look at the most popular nano and pico reef tank kits and see which ones are best suited for your needs and budget. All of these are great options for mini reef habitats and come with the basic equipment needed to start a coral tank. You can usually expect to get your tank, hood or cap, filter, and lights in these types of kits.

However, unlike aquarium starter kits, small reef kits do not usually come with gravel or decorations. You will still need to choose the substrate, live rocks, corals, and fish for your tank, and many aquarists also upgrade or customize their filters and/or light systems further once their tank has matured.

1. Coralife LED BioCube

  • Capacity: 16 gallons
  • Dimensions: 17.5 x 16.5 x 15 inches
  • Features: glass tank, built-in hinged hood, LED light with self-timer and actinic moonlight, compact internal filter with customizable chambers, submersible pump with dual inlet nozzles

Great option for a starter reef tank.

Attractive glass aquarium uses a honeycomb pattern to hide the rear filtration compartment and water line Powerful 3-stage filter gives you mechanical, chemical, and biological filtration and has room for additional media Kit is adjustable for use with other fluval products such as water heaters and protein skimmers The filter inlet may need to be adjusted if you are keeping delicate fish or shrimp that could be damaged by the strong suction. Rear filter compartment is small and can be difficult to reach with large hands Lights are not very durable and seem to require replacement more often than they should

3. Marineland Contour Aquarium Kit

  • Capacity: 3 gallons
  • Dimensions: 12.05 x 11.82 x 11.62 inches
  • Features: Glass tank and lid, 3-stage filtration system, Compact LED track light with blue moonlight

If you want a peak sized reef tank under 5 gallons for your desk or office, then the Marineland Contour is the top pick on my list. The kit includes a glass tank with rounded corners and the attractive LED track light highlights all areas of the tank. The 3-stage internal filter is built into your tank and is slightly customizable.

This tank has a very modern or Art Deco style, and the transparent top makes it easy to see from any angle. I really like the look of this little tank, and it’s one of the least expensive on my list! However, there aren’t many fancy extras and it’s a bit too small to hold fish with their soft corals. It is an ideal choice for a coral beak tank.

Compact glass tank is ideal for an office reef aquarium desk Clear glass cover allows you to view your tank from any angle Hinged track light is attractive and swings out of the way when you need to reach inside the tank The filter is not replaceable so if it breaks there is no way to swap it out for a new one The LED lights are not replaceable and the blue LEDs don’t seem to last long The glass lid design makes it awkward to add a heater to this tank, as the lid will not close completely if there is a wire in the way.

4. Fluval Flex Aquarium Kit

  • Capacity: 15 gallons
  • Dimensions: 16 x 15 x 15 inches
  • Features: curved glass tank, built-in hood, remote controlled LED light, 3-stage internal filter, dual adjustable outlet nozzles

If you want the best looking nano reef kit, the fluval flex might be the choice for you! This modestly priced kit comes with a beautifully curved glass aquarium with an integrated, nearly invisible hood.

The high-quality LED light is ideal for maintaining corals and can be adjusted via remote control, and the built-in filter compartment also fits Fluval heaters and protein skimmers (not included). The rugged 3-stage internal filter is customizable and contains stages for mechanical, chemical, and biological media.

However, one thing to keep in mind is that the actual capacity of this aquarium is only 10 gallons. The internal filter compartment holds additional water but reduces the amount of space in the main section for fish and corals. It’s very easy to accidentally overstock this tank, so use the 10-gallon capacity when choosing your tankmates to avoid problems.

Unique curved front aquarium enhances the view and makes your tanks appear larger Separate rear filter compartment is customizable and also has room for an aftermarket hot water heater LEDs are built into the hood and can be adjusted with the remote remote Does not come with heater or protein skimmer, but Fluval products can be added aftermarket. The rear compartment reduces the actual capacity, so this tank only holds about 10 gallons of water and not the advertised 15. The feeding hole in the hood is small and a bit awkward to use, which could be annoying if you’re keeping corals and fish.

5. Red Sea MAX NANO Rimless Aquarium

  • Capacity: 20 gallons total (16.5 gallon tank + 3.5 gallon sump)
  • Dimensions: 18 x 18 x 18 inches
  • Features: glass cube tank, rear sump filter, surface and protein skimmers, 3-stage internal filter, WiFi-enabled advanced LED light with adjustable color channels, automatic water fill system

If there is one tank in my heart that I can wholeheartedly recommend, it is this premium Red Sea aquarium kit. The Max is a top of the line kit that includes a sump filtration system connected to an automatic water fill system, so your tank will always be at the correct water level. This is a completely plug and play marine reef kit!

It’s so feature-packed that I can’t even list them all here. Standout features are the sump, customizable advanced filtration system and very high quality WiFi enabled LED light system with adjustable color channels. This kit also comes with protein and surface skimmers.

The only thing missing from this kit is a water heater and chiller unit for cold water species, and those aren’t standard on reef tank kits anyway. The main disadvantage of this tank is the price; it is substantially more expensive than the other options. But if you really want to have the best nano reef you can keep, this is the kit to get!

The most advanced tank on the list with multiple premium features like an automatic water fill system Includes an integrated sump filter with media compartments High quality LED light offers advanced control with reef and channel specific light settings adjustable color It holds 20 gallons of water, but the actual capacity of the aquarium is 16.5 gallons as the sump holds 3.5 gallons. Does not include water heater or cooler, so you may need to purchase them separately. The premium tank is priced higher and may be out of the budget range for many novice reef tank owners

6. Marineland LED Aquarium Kit

  • Capacity: 20 gallons
  • Dimensions: 24 x 12 x 16.5 inches
  • Features: rectangular glass tank, hood with built-in LED light, clip-on HOB filter

20-gallon reef tanks are the ideal size for nano aquariums, and this starter kit from Marineland is a great place to start building your coral reef. For a very reasonable price, you’ll get a standard sized glass tank with a hood and integrated LED lamp. The slim clip-on HOB uses replaceable cartridges and is easy to access.

However, this is just a basic setup and you’ll need to add an Actinic Moonshine if you want a thriving coral population. The filter does not have room to hold biological media so adding a sump filter would be a very good idea and would also stabilize the water chemistry.

If you want an all-in-one kit, this may not be the best option for you, but it’s a great way to save some money on a nano kit while customizing your reef tank with additional add-ons. Personally, I’d get rid of the clip-on filter and replace it with an external canister system and add a sump filter to improve water quality.

Standard size 20 gallon tank makes customization fairly easy Integrated hood holds the LED light and opens for easy access to your tank Slim back clip filter provides basic 2-stage filtration and uses replaceable cartridges Very basic setup and a better option for fish than coral. The LED light does not include actinic moonlights, so you will need to add a moonlight for your corals. It does not come with a heater, and the filter is simple and contains no additional biological or chemical filter media.


If you are looking to start a 30 gallon or smaller reef tank then you should consider purchasing a nano or pico reef tank kit. Getting a kit is easier than buying the kit one piece at a time, and you can be sure the filter and lights will fit your tank. However, small marine tanks are more difficult to maintain than large ones.

If you’re still not sure which tank kit is best for you, consider the following:

  • The Red Sea Max is a premium reef kit and includes just about everything you need to keep your corals and fish happy and healthy.
  • However, if Max is beyond your budget, consider the Fluval Flex or Evo kits depending on the size and look you prefer.
  • The BioCube is excellent value for money and the Marineland is a nice base setup.
  • For extra-small reef tanks, consider the peak-sized Contour.

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