Sink or Swim

Since excess proteins in a tank can be disastrous for its inhabitants, hobbyists will need the best protein skimmers available to keep their aquariums thriving


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An ample serving of protein may be great on your dinner plate, but in aquariums, protein needs to be kept in check.

Excess proteins in an aquarium may become considerably dangerous because they produce high levels of ammonia as they break down. When fish relieve themselves through their urinary tracts, gastrointestinal systems and even over their gill membranes, the effluent contains a considerable quantity of the building blocks of proteins. When this toxic compound builds up in a captive environment, it can quickly kill or damage livestock. Protein build-up is doubly dangerous in a marine habitat. Reef organisms of all types may succumb to high ammonia levels, but coral, in particular, is most likely to die.

The obvious solution to this dilemma is to change water, but that is not always possible at a moment’s notice. A better choice would be to constantly remove the toxic ammonia from the water, rather than all at once. This is when the protein skimmer comes into play.

It is true that chemicals and resins may be used to bind up ammonia, and thereby make it non-toxic or unavailable to wreak havoc on the livestock. This does not mean that the ammonia is not still present—it is. Only a water change can remove it completely, unless you use a protein skimmer.

Protein skimming is simple and complicated, all at the same time. Protein molecules are attracted to air bubbles because opposites attract. Have you ever seen a thin, hazy sheen on the surface of a fish tank? It is frequently visible just after feeding. Such a film is usually oil from the food, your hands or even carried through the air and landing on the water’s surface. It stays there rather than mixing with the water because oil is not soluble in water. Oil is organic, and it will lie on the water’s surface for two reasons. It is lighter than water, so it floats, and it consists of molecules that are attracted to water, but only on one end. If you apply a material that this floating oil is attracted to even more than water, you can skim it off the surface. A sheet of uncoated paper, such as a newspaper, usually does the job. Carefully lay the paper on the water so it floats. Then, remove it quickly before it sinks.

Unfortunately, newspaper won’t attract or collect the protein produced by organisms, since it is already thoroughly mixed in the water column. Bubbles, on the other hand, will. Bubbles can draw out the protein without using chemicals. Why are proteins attracted to bubbles? Proteins are rather simple molecules for the most part, but they are large enough to exhibit different characteristics from one segment to the next. Basically, they have one part that has an electrical charge, while the other part does not. The charged portion is attracted to water molecules. The uncharged segment is trying to escape water, and the surface of a bubble is a good way to do that.

When a protein skimmer produces sufficient bubbles of the proper size in an enclosed cylinder, a physical reaction can take place. The uncharged portion of a protein molecule sticks to an air bubble and rides up into the collection cup at the top of the protein skimmer. The only thing that should reach this cup is foam or bubbles—never liquid. If you turn up the flow rate too fast in a skimmer, water will flood the cup. The setting needs to be just right, if the skimmer is to work properly.

Of course, if a tank is well managed, it’s entirely possible that there is no protein to skim, in which case, bubbles will not reach the cup. Instead, they merely dissolve in the cylinder because they are too heavy. Proteins attached to the bubbles’ surfaces actually make them lighter, hence they rise higher in the cylinder.

Many things influence how efficiently a protein skimmer works. First and foremost, a skimmer must be designed properly to work properly, and retailers should only sell devices they believe in. You can make that decision based on a variety of criteria. As with anything else sold in the aquatics trade, skimmers are available at various price points. There are cheap skimmers and high-end skimmers, but, if everything else is equal, I would opt to offer customers the more high-end skimmers.

I prefer skimmers that have their own dedicated pump included in the package. The manufacturer should know which pump works best with its skimmer, and that pump should come with it. Retailers might think they will make more money selling the skimmer and pump separately. However, they should keep in mind that they might eat up all that profit by spending precious time explaining to customers what pump to buy, how to set it up, what plumbing supplies they will need, and so on.

Another point to keep in mind is the uniqueness of every individual reef setup. I would recommend protein skimmers for any reef tanks of 75 gallons or larger. However, the efficacy of the device will depend on a number of interchangeable factors that vary from one setup to the next. I prefer skimmers that sit on the floor outside the sump, but most people use them in a sump. As a bonus, protein skimmers also oxygenate the water and reduce the carbon dioxide level, thereby helping to maintain a higher pH value.

The reasons some people have better or worse luck with their protein skimmers are due to individual differences. Skimmers do their jobs better at a high pH. They work better at a higher specific gravity. They work more efficiently at lower temperatures—never above 80 degrees Fahrenheit, with 76 to 78 being optimum. They work better when there are more organics to be skimmed. And, in general, taller skimmers work better than shorter ones, all else being equal.

Stores should stock skimmers that fit a standard-height cabinet stand, as well as at least a few that will only sit beside a stand. These are usually the best choice for most people, even if they don’t like the aesthetics. As for the internal features, there are several concepts out there on the market: old school counter-current, venturi, aspirator, Beckett, spray injection, etc.

I would settle on the venturi skimmers as your main selling item, with maybe one or two of the others on display in case someone shows an interest. There are, of course, skimmers that hang on the aquarium, and these can work very well for those customers who do not have a sump.

Lastly, some people object to the smell given off by a well-working skimmer. For them, you can offer skimmate lockers as an auxiliary item. They trap the gas and neutralize it with charcoal.

All in all, protein skimmers are a necessary evil for most marine hobbyists. You need to be at the forefront of what’s happening in the skimmer world, so you don’t get caught with outdated products.


Edward C. Taylor has been in the pet industry for over 30 years as a retailer, live fish importer and wholesaler, and fish-hatchery manager.

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