FREQUENTLY ASKED QUESTIONS
Protein skimmers (in one form or another) have been around at least 40 years. There are misconceptions about what they can and cannot do
What follows are a group of basic questions, the answers to which will hopefully prove useful in eliminating these misconceptions and fostering a more complete understanding of the nature and function of protein skimmers.
What is a protein skimmer?
Why use a protein skimmer?
How does a protein skimmer work ?
What kind of protein skimmers are there?
Who needs a protein skimmer ?
What are the location requirements?
How long should I run the skimmer?
Is it possible to over skim ?
What maintenance is required ?
Is ozone required ?
WHAT IS A PROTEIN SKIMMER?
A protein skimmer is a device that concentrates and removes dissolved material from water by floating it to the surface via an accumulation of air bubbles. It basically consists of a tube (the contact column) for the concentration of bubbles, an aeration device (e.g. airstone, venturi), a water inlet and outlet, and a removable collection cup. Some units may add additional features, but the basic design is the same.
The name "protein skimmer" is essentially misleading. These devices do not skim the water surface and they, in fact, remove more than just protein. A more appropriate name for a protein skimmer is "foam fractionator," due to the fact that the bubble concentrations (foam) serve to separate (fractionate) dissolved material from the water
Most of this material, termed DOC (Dissolved Organic Carbon) by scientists, is produced by the biodegrading activity of certain bacteria, but some is released by algae and other organisms as part of their normal bodily function. Because the DOC is dissolved in the water, they cannot be removed by traditional mechanical filtration methods. back to top
WHY USE A PROTEIN SKIMMER?
A foam fractionator removes the DOC that a traditional mechanical filter does not. The accumulation of DOC in water, among other things, inhibit the nitrifying bacteria and increase the biochemical oxygen demand (BOD a way of measuring water pollution), thus lowering water quality. Water becomes discoloured and foul smelling.
Furthermore, some types of DOC can be degraded by bacteria in the water via a process called Mineralization. Heterotrophic bacteria convert DOC into toxic substances such as ammonia and carbon dioxide, while consuming vital oxygen in the process.
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HOW DOES A PROTEIN SKIMMER WORK?
The two keys to effective protein skimming (or foam fractionating) are air bubbles and surfactants. DOC are surfactants--compounds whose surface is defined as "active." This means that when a surfactant compound is in water, its non-polar end, labeled hydrophobic or "water hating," seeks the surface, the air.
Normally, the only "air surface" in the aquarium is the surface of the water. However, if bubbles are added to the water, more air surface is created. More air surface means more surfactants (DOC) are attracted and removed.
Smaller bubbles have more surface area than larger ones. Also, the longer the bubble stays in the water, the longer its contact time with the surfactant. Bubble size and contact time determine how effective and how fast a skimmer will work.
Protein skimmers take advantage of these physical properties by producing a large amount of bubbles in a controlled space--the contact column. This serves to concentrate the bubbles and the DOC. As the bubbles in the column rise, the surfactants (DOC) attach to the surface of the bubble so that its hydrophobic end is "inside " and in contact with the air. The bubble carries the DOC to the water surface, where it forms foam. The air-preferring DOC stay at the surface rather than redissolve into the aquarium water.
This process is repeated thousands of times a minute and a large amount of foam can be generated. The foam grows over time, is collected in a cup or other such vessel, and is removed by the aquarist at regular intervals. While there is considerably more physics involved in trying to produce the right bubble size and in the determination of other factors as well, this is the basic operative mechanism involved in protein skimming. The goal of any good skimmer? To produce a great number of small bubbles in the contact column.
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WHAT KINDS OF PROTEIN SKIMMERS ARE THERE?
The difference between brands of skimmers is most evident in the ways they move water and generate bubbles. There are two basic types of protein skimmer: co-current and countercurrent. Current pertains to water flow, while "co-" or "counter-" indicate whether the air is moving with or against the water current, respectively. Either of these units will require an airstone and air pump to generate the bubbles needed for operation.
Other skimmer models employ a venturi air injection system instead of an airstone to produce bubbles without an air pump. These pump water through an injector via a water pump. The injector has a narrowed pathway in its center and an additional opening that admits air into the unit. Typically venturis generate back pressure, causing the the pump to work harder, and reduce the circulation rate. The Airmaster Aquafoil works in a completely different way and generates little or no back pressure, which puts less strain on pumps and more crucially, maintains full flow rates.
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WHO NEEDS A PROTEIN SKIMMER?
Another misconception of foam fractionators is that they will not work in freshwater. The fact is, most units available today will function in freshwater. It is, however, more difficult for a counter-current or Venturi skimmer to generate small bubbles in freshwater and it cannot do it as quickly or efficiently. The Improved technology of the Airmaster Aquafoil has made it possible to skim off harmful protein compounds from freshwater by producing microbubbles from the outset, so it produces foam when other protein skimmer can't.
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WHAT ARE THE LOCATION REQUIREMENTS?
The range of foam fractionators we produce all require the water to be pumped through them. So always after the pump.
HOW LONG SHOULD I RUN THE SKIMMER?
Twenty four hours a day. There will be some periods of the day when the skimmer will produce more foam than others, but that is natural.
IS IT POSSIBLE TO OVER SKIM?
No. In addition to DOC, protein skimmers can remove other substances, e.g. trace elements. However, these substances are easily replenished.
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WHAT MAINTENANCE IS REQUIRED
To retain its effectiveness, a protein skimmer must be clean to allow the bubble to form at the top and flow to the collection cup. A short time after installation and continuous use, a greenish brown sludge will begin to form on the walls of the skimmer. This should be cleared off regularly. .
IS OZONE REQUIRED WITH MY SKIMMER ?
It is not necessary to use ozone with a protein skimmer. Although ozone can encorage additional oxidation and breakdown of large molecules making. them more susceptible to removal by skimming.
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