The nano reef aquarium is arguably the most challenging type of aquarium. These aquariums, generally considered to include any marine aquarium featuring invertebrates with a capacity of less than 30 gallons, have all the demands and complexities of a larger reef aquarium. Additionally, their small volume means that any issues with water quality can rapidly reach critical. A protein skimmer is a very useful tool, and could make the difference between success an failure in this challenge.
What Protein Skimmers Do
Protein skimmers are important, if not critical, in all marine aquariums. They function through a process called foam fractionation. In fact, some models sell under the name foam fractionators. In this process, a pump generates tiny bubbles, which slowly rise through a column of water. Where the bubbles' gasses meet the water, surface tension attracts and collects various biological waste products, including proteins and other organic compounds. The bubbles clump together at the water's surface, where they form a foam. As the foam builds up, various plumbing fixtures drain it away, removing the organic wastes. This improves water quality by removing contaminants, as well as organic compounds that can bread down and release ammonia.
Is it Nescessary?
Different experts have different opinions on the necessity of protein skimmers. Author Jim McDavid of Tropical Fish Hobbyist magazine considers protein skimmers essential for nano reef aquariums. Meanwhile, Scott W. Michael of Aquarium Fish USA Magazine holds them not to be quite mandatory. However, even the more moderate sources like Michael still consider them useful and a good piece of equipment. Keep in mind that while other types of aquarium filtration can perform some of the same functions as a protein skimmer, there's no reason you can't combine them with other types of filtration.
Skipping the Skimmer
If you do decide to skip the skimmer, you will have to make certain concessions. First, you will have to perform water changes slightly more often. Ideally, in a nano reef aquarium without a skimmer, change 10 percent to 20 percent of the water weekly to compensate for the lack of a protein skimmer. Additionally, with a protein skimmer, you will have a more narrow margin for error in aquarium maintenance. For example, if you've overstocked or overfed your nano reef aquarium, water chemistry will degenerate much more quickly in the absence of a protein skimmer.
Size of Your Skimmer
You have two considerations when selecting a skimmer. First, you should get the most powerful protein skimmer that you can get. Jim McDavid of Tropical Fish Hobbyist recommends getting a protein skimmer rated for at least a 100 gallon aquarium. Since nano reef aquariums have a small volume of water, and contain such sensitive organisms, you need a powerful skimmer -- or alternate filtration systems -- to provide pristine water. For the second consideration, you need to find a protein skimmer that fits comfortably within your setup. With many marine aquariums in general, and nano setups in particular, the aquarium uses a piece of equipment called a sump. Sumps allow you to attach aquarium gear like protein skimmers to a separate water container, often hidden within the aquarium stand. At the same time, some skimmer designs are more compact than others. For example, a venturi skimmer will work more efficiently than an airstone-drive skimmer of the same size. Unfortunately, more powerful-for-their size skimmers often cost more. You may need to compromise between power and space.