While it's no secret that we all love our reef tanks, it's also no secret that a reef junkie is never satisfied. We're always looking for the next piece of equipment, the next challenge or another place in the house where we can stick a tank. It should come as no surprise then that we're seeing a rise in the popularity of diminutive pico reefs across the hobby.

If you've been thinking of setting up a pico, you're in the right place. We're going to talk about the choices at hand for equipment, stocking options and of course the different tanks that make great choices for a pico setup.

First, A Word of Caution

Pico tanks aren't for the faint of heart. As you likely know, the larger the volume of water in a reef environment, the more tolerant the system is of changes. With many successful pico aquariums falling in the 2 to 4 gallon range, it's obvious that an excess of water will never be something that you'll enjoy in this project.

While the startup cost for a pico tank can be lower than what you would spend on a nano or larger setup, that money savings is certainly not a rule. I have seen many pico tanks that total into the thousands of dollars because of lighting, custom overflow systems and chilling systems to combat the heat generated in such a small space.

All of that being said, look at a pico as a project that you do because you enjoy the challenge, not because you think it will be easier or might save you a few bucks.

Now Let's Talk Tanks

As a general rule, anything below five gallons falls into the range for a pico tank. You'll need to fulfill the same requirements with a pico tank that you do with one of any other size (with a couple of exceptions). That is to say that you'll want to make sure that you have lighting that is appropriate for your livestock, a significant amount of live rock and/or sand, and of course water circulation.

There are a lot of all-in-one systems that work great either by themselves, or as a starting point for further customization. Innovative Marine's 4-gallon Pico is one such option, providing you with lighting, filtration and even a media basket. The clean look of the all-in-ones is very popular in the pico hobby, and you'll often find this sort of design used and modified to great results.

The three-gallon Picotobe from JBJ takes a slightly different approach, opting for a hang-on-back filer rather than an all-in-one system. The potential advantage here is that you can readily use a number of different hang-on-back filters if the included option no longer fits your needs.
Of course you can always take the bare-tank approach and then choose your lighting and filtration options as a blank slate. The Mr. Aqua brand of tanks are a great option here not only because of their high quality construction, but also because of their unique shapes and overall beauty.

Lighting Your Way

One of my personal favorite parts of pico tanks is the wide variety of lighting options that you have. While there are dedicated lights (such as the Skkye series from Innovative Marine) you're certainly not limited to only a single system. Many pico fans have had great success with small T5 fixtures, and PAR 38 bulbs are also very popular. Of course, if you're wanting the wow factor, it's incredibly hard to beat the A150 from Kessil.
Whatever choice you make, you'll need to take into consideration the heat that the light will produce. Again, because of the small volume of water that we work with in pico systems, evaporation can become a major issue.

Staying Stable

As we talked about before, one of the biggest challenges of these tiny tanks is keeping the levels stable. Heating, cooling and salinity are going to require a fair amount of attention, and systems to automate these controls are likely going to become your best friend.

Auto top-off systems, such as the Tunze Nano Osmolator is a great option for keeping your water level where it needs to be. Tunze has done an awesome job of creating a tiny system that works really well with rimless tanks.

There are great options for heaters in pico tanks, many of which can be hidden behind the wall in an all-in-one. The Cobalt Aquatics Neo-Therm is my personal favorite, but Hydor, Hagen and Eheim all have great options as well.

Unfortunately, the bigger problem than heating a pico is often keeping it cooled. Because of the close proximity of circulation pumps and the lack of size, pico tanks can tend to run somewhat warmer than we want them to. The IceProbe and MicroChiller systems, both from Coolworks, are great options for temperature regulation, and they're designed to work with smaller systems.

Of course the single largest investment (and likely the best one) you could make for your pico is a monitoring and controlling system. The ReefKeeper Lite system is my personal favorite for picos because of its ability to regulate temperature effectively without breaking the bank.

Stock Options

Now for the fun stuff! Pico tanks, because of their tiny size, aren't going to be the best option for most fish. You should always keep in mind that your ocellaris clown might be tiny today, but she's going to grow and need a few more gallons than a pico can provide. With that in mind, about the only fish that will be happy in a pico aquarium is something from the goby family.

As Metrokat pointed out in her recent blog post about fish choices for nano tanks, gobies are a perching and hopping fish. As such they don't require a lot of swimming room, but you'll definitely want to give them some live rock "perches" to make them happy.

Given that there are very limited options for fish in pico tanks, you'll find many of us pico enthusiasts opting toward coral-only setups. For my own system, a two-gallon all-in-one with PAR 38 lighting, I've found great success with waving hand corals, mushrooms and even a single-headed duncan coral. While it can be challenging to find areas of lower flow and appropriate lighting, many corals will thrive in pico systems, provided you pay careful attention to your parameters (especially salinity).

Wrapping Up

Whether you're just looking for a challenge, or maybe wanting a more interesting option for a frag and growout tank, pico reefs are a rewarding project that any reef junkie can appreciate. Like any reefing project, research and patience need to be your guides, but hopefully you now have a better understanding of where to start.