Do You Need a Protein Skimmer?

You may have been told you need a protein skimmer for your aquarium. You might have also heard that protein skimmers are not necessary. What is a protein skimmer and is it necessary for your particular aquarium?

Protein skimmers are a special type of aquarium filter for saltwater aquariums. How do they work? The short answer is they create bubbles through mixing air and water and the waste clings to the bubbles.

Here is the longer, scientific answer. Waste compounds in aquariums are often polar molecules—they have two sides with different electrical charges. One side is hydrophilic (attracted to water) and the other is hydrophobic (repelled by water). As a consequence of this, a lot of the dissolved waste can collect at the surface of the water where one side of the molecules can touch the air and the other side can touch the water. Think of the oil-like scum that you can see on the surface of a dirty pond or aquarium.

The protein skimmer uses an open-top tube filled with bubbles with a cup over the open top. The waste molecules are attracted to the bubbles because there is air inside of the bubbles and water outside of the bubbles. As the bubbles rise to the top of the tube they pop and release all of the waste on their surfaces. The waste is collected in the cup. Because of the higher surface tension of saltwater compared to freshwater, Protein skimmers work nowhere near as well in freshwater aquariums so we do not recommend them for freshwater aquariums.

If you have a saltwater aquarium, it is not absolutely necessary to have a protein skimmer. However, your aquarium requires filtration, and for a variety of reasons protein skimmers are often the easiest and most affordable way to filter a saltwater aquarium.

Here are some of the advantages of protein skimmers:
  • Protein skimmers are one of the only filters that actually remove the waste from the water rather than holding it in a cartridge or media until you manually replace the filter material. Keep in mind; filters are only trapping fish waste (poop) and uneaten food. When you trap this waste that is not immediately removed, nitrates, nitrite, ammonia, and phosphate can leak back into your tank.
  • Protein skimmers do not require purchasing or replacing any filter media. The upfront cost may be high, but the long-term cost will be lower.
  • Protein skimmers do not add any chemicals or foreign substances to the aquarium water.
  • Protein skimmers oxygenate the water and can increase pH.
  • Protein skimmers remove waste within minutes unlike bacteria and algae filtration that can take hours or days.
  • Protein skimmers increase water clarity for better viewing.
Because of all these benefits, protein skimmers are the most popular saltwater aquarium filtration devices, and we do recommend them for all saltwater aquariums. Protein skimmers are even more important when you have a reef aquarium as coral is very sensitive to water quality.

For small aquariums less than 50 gallons, some saltwater aquarists choose to either not use a protein skimmer, or they just use a small protein skimmer. Instead of relying completely on a skimmer, they do more frequent water changes. Part of the thinking with this decision is that with small all-in-one tanks the skimmer has to be small to fit in the back compartment. Small skimmers are not that effective (because the effectiveness of a skimmer is largely proportional to the size of the skimmer). Having a larger hang-on skimmer can be a better choice functionally, but it also can be a huge eyesore. However, even with small aquariums, we do recommend using a protein skimmer. Not only will a small skimmer remove some waste, but it will also oxygenate the water and help to raise the pH.

With larger aquariums, especially reef aquariums, protein skimmers are a must. Not only are protein skimmers the best form of filtration for saltwater aquariums, but the only other decent alternative is large frequent water changes, and with a big aquarium this is quite a task. We recommend getting the biggest protein skimmer you can afford.

Further Reading