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Protein Skimmer

Filtering Your Aquarium Water

(The First Tank Guide)

What Is a Protein Skimmer?

Protein skimmers remove excess protein waste from salt water (marine) aquariums by pushing air through a column of moving water. The proteins adhere to the air bubbles and are carried up to a catch of some sort (a cup or bowl). This catch can be removed and cleaned.

Different varieties of protein skimmers can mount inside the tank, over the back of the tank, as part of a power filter, external to the tank, or even in the sump of a trickle filter.

Protein Skimmer Diagram

How Does a Protein Skimmer Work?

Protein skimmers use the surface tension of the water in marine aquariums to pull free-floating proteins and other waste into a container where the waste can be removed.

Simpler protein skimmers use an air stone (usually a wooden one to produce finer bubbles) connected to an air pump and allow water to flow through a tube where the bubbles pass through the water. As the bubbles rise in the water, they collect proteins on their surface and lift the water. The bubbles can continue out of the top of the protein skimmer and burst into the catch or holding cup, releasing their cargo of protein waste. The water, meanwhile, is diverted into the tank through some kind of baffle.

More advanced protein skimmers inject air into a fast-moving stream of water from a water pump, forcing a more reliable turn over of the water in the column where the air bubbles are, exposing more protein laden water to the bubbles so they can remove that protein.

The most advanced protein skimmers force highly aerated water downward from a water pump, causing the bubbles to fight their way back up against the current. This increases the time the bubbles are exposed to the water, and therefore improves skimmer efficiency.

What Maintenance Does a Protein Skimmer Require?

Air stone driven protein skimmers require regular changes of their air stones as the stones get plugged with algae, bacteria, various debris, and the same proteins the protein skimmer is removing to maintain free air flow. The frequency at which your air stone needs to be changed will vary depending on tank load, feeding habits, and other aquarium tank maintenance. Protein skimmers run with an air stone also require high-quality air pumps to provide sufficient and consistent air flow.

Protein skimmers that use a water pump need to have their pump serviced regularly to insure that the impeller is moving freely and that the intake is not clogged with debris. Cleaning brush kits are available at most pet stores to facilitate this procedure.

You will also have to clean out the collection cup from your skimmer on a regular basis. Depending on your tank load and the style of skimmer, you may need to change this as often as once a day or as rarely as once a month. Keep a close eye on the cup, however, as the maintenance could change dramatically for even the slightest change in tank conditions.

What Should I Be Aware of with a Protein Skimmer?

Protein skimmers only work in salt water, or under very high pressure in fresh water. This is because the surface tension of the water changes with salinity or pressure. if the surface tension of the water is not in the correct range, the protein skimmer cannot work.

If you are trying to maintain a Berlin style reef tank, 10 to 14 inches of skimmer column height is recommended for every twenty gallons of water. This will remove a great deal of waste before it has a chance to start to decompose and threaten your corals with Nitrite, Nitrate, or algae blooms.

Protein skimmers provide only mechanical filtration (the removal of suspended particulate matter from the water), despite some claims that they provide chemical filtration. The result of filtration with a protein skimmer is similar to some forms of chemical filtration, but the way a protein skimmer actually works in mechanical in nautre.

"Thanks for your web site!"
May 25, 2003
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"Thanks for the info, very helpful, and you have dispelled the myth about fish growing into tank size. Shame though, you could end up with an interesting rectangular fish. "
June 9, 2003
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