Protein Skimmers

Do I Need a Protein Skimmer?

If you have ever seen foam form as waves crash onto a beach, you have seen foam fractionation at work. Foam fraction-what? Foam fractionation. Through this process, air bubbles entrained into the water chemically remove organic compounds. Surfactants – organic molecules with nonpolar portions – are attracted to the surface of the bubbles and chemically adsorbed. The bubbles and the adsorbed organic compounds then float to the surface of the water where they coalesce into a foam.

Through the use of a protein skimmer, this process can be harnessed to the benefit of your saltwater reef aquarium. Protein skimmers chemically remove dissolved organic compounds through the process of foam fractionation. Air bubbles are injected into the vessel of the skimmer via one of several methods (more on this later). These bubbles attract surfactants and the resulting foam overflows into a collection cup. The dedicated reef keeper then regularly cleans the protein skimmer to remove the buildup of organic matter. Protein skimmers can greatly reduce the amount of organic waste in your reef aquarium, thus reducing the overall nitrogen load. When used in conjunction with mechanical and biological filtration, a skimmer is crucial for maintaining excellent water quality parameters.

Types of Protein Skimmers

There are several styles of protein skimmer and many names used throughout the aquarium hobby to describe them. They all work by drawing air into the skimmer vessel to create fine bubbles. The type you use will depend on many factors including:

• The size of your system
• The amount of space available
• And, largely, your personal preference

There are three general classes of protein skimmer:

• Venturi-driven
• Needle wheel
• Downdraft (sometimes referred to as Environmental Tower Skimmers or ETS)

And several different styles:

• Hang on back (HOB)
• In sump (or internal)
• External

How Venturi Skimmers Work

Venturi-driven skimmers use a venturi device to inject air bubbles into the system. Venturis work by constricting the diameter of piping that water travels through. As water passes through the constricted portion of the venturi, the velocity of the water increases, which draws in air through a small air intake hole and produces very fine bubbles.

How Needle wheel Skimmers Work

Needle wheel skimmers create bubbles by pulling air in at the skimmer pump’s volute. A modified impeller chops the mixture of air and water into fine bubbles which enter the skimmer’s contact chamber. There are a plethora of needle wheel impeller options, including a rich assortment of DIY contraptions.

How Downdraft/ETS Skimmers Work

Downdraft skimmers, or ETS skimmers, entrain air as water cascades down over a tower of bioballs. The resulting bubbles are then pushed back up to form the fractionating foam. These skimmers can be quite temperamental, and that’s saying something as skimmers, in general, are known for their finickiness.

Beckett Skimmers

Downdraft skimmers include a subcategory of note: Beckett-driven skimmers. These work in the same fashion as downdraft skimmers; drawing in air through a specialized device called, you guessed it, a Beckett. A mixture of air and water cascades over the Beckett device creating fine bubbles. This device will also require regular cleaning, along with the skimmer, to maintain optimal functionality.

All these skimmer types are offered in a range of styles. Whether you choose in-sump, hang-on back (HOB), or an external skimmer will depend on your specific setup and space availability.

What Do Protein Skimmers Remove

Protein skimmers remove just that – proteins; organic waste material in your system. The list is long and debatable, basically including any substances that are hydrophobic in nature. It is important to consider what your skimmer may remove as you manage your reef system:

• Coral and fish waste products
• Medications – if you are treating your system, give your skimmer time off for the duration.
• Trace element additives (as they form complexes with proteins)
• Organic phosphates, bacteria, and algae – though to a much lesser extent

Personal anecdote coming: I often add a commercial trace element supplement that is blue in color. When I add this product with my skimmer running, a blue skimmate results, letting me know I am wasting my money and time. I’ve found it best to dose the trace vitamins and minerals with the skimmer off. For convenience I do this on days I am cleaning my skimmer. If you are adding an organic product or feed (like microalgae), do yourself a favor and turn your skimmer off for a bit.

Tips for Setting Up Your Skimmer

There are several important points to consider when setting up your skimmer. Each of the following will affect the efficiency of your protein skimmer:

• Location – Whether they are in sump or external, your protein skimmer needs to be situated higher than its discharge destination. This is because skimmers operate at ambient pressure. It is also important that effluent water flows into a sump or other area, allowing for the dissolution of microbubbles, which could cause harm to aquarium animals. You’ll adjust your skimmer via the effluent valve – restrict flow and you’ll increase the volume of water in the skimmer chamber, increase flow and you’ll reduce that volume. Whenever adjustments are made, allow some time for the skimmer to settle and reflect those changes. Plan to check on it regularly to make sure no problems are observed.
• Contact time – Longer contact time allows more opportunities for proteins to come in contact with the bubbles and to attach themselves. Contact time greatly affects the amount of organic material removed from the water. Larger skimmer contact chambers generally allow for longer contact times.
• Height and diameter of the reaction chamber – The height and diameter of the reaction chamber directly affect contact time, which, as mentioned above, play a big part in determining skimming potential. A larger reaction chamber will help increase contact time.
• Bubble size – Bubble size is also critical to skimmer efficiency and function. Smaller bubbles will have a higher surface area to volume ratio than larger bubbles, allowing the collection of more material. Side note: bubble size also factors heavily in the reason protein skimmers do not work effectively in freshwater. The density of the water affects bubble size and stability. More bubbles will form in saltier water.

Troubleshooting

• My skimmer is running wet and losing water from the collection cup. Help! – Beware of wet skimming. This usually occurs when the water level in the skimmer is too high and water, instead of skimmate, pours out of the collection cup. This can be a major problem as wet skimming, left unchecked, can result in catastrophic water loss from your system. After cleaning or other maintenance, always monitor your skimmer to look for any changes in water level. The perfect set point for each skimmer will be a little different and you’ll need to spend time dialing yours in just right when you first set it up and likely from time to time thereafter especially following maintenance.
• My protein skimmer was skimming perfectly and suddenly stopped! What happened? – Adding organic material (such as food, reef supplements, phytoplankton, etc.) to your tank can temporarily affect skimmer function. Don’t be alarmed if your perfectly dialed-in skimmer suddenly stops skimming when you feed. It will resume normal functioning after a short period. Do not adjust it immediately after feeding.
• Do you have any tips for optimizing skimmer function? – Generally, you can manage your skimmer’s functioning by adjusting the height of the water in the chamber and the quantity and size of bubbles. To optimize skimming, adjust these components, one at a time. Allow more water to flow through the skimmer to lower the water level, restrict it to increase the water level. Adjust air intake to manage the quality of your bubbles. After making any adjustment, allow some time for the skimmer to level out and be prepared to continue fine-tuning until you get it skimming right in that sweet spot. Dry, light to dark brown foam is the goal.

Protein Skimmer Maintenance

A protein skimmer will appeal to many aquarium buffs as it does require regular maintenance. This is not a “set it and forget it” component to your system. As skimmate, the gunk removed by the skimmer builds in the collection cup, it will require removal. Skimmate will generally appear light to dark brown in color and is usually pretty slimy but relatively dry. Built-up material on the sides of the skimmer will eventually succumb to gravity and fall back into your system, defeating the purpose of skimming it out.

In many small skimmers, the cup can be removed for cleaning and the inside of the skimmer gently wiped clean. Simply shut power to the skimmer pump, remove the cup, rinse thoroughly with fresh water, wipe sides of the skimmer, and then replace the collection cup. Return power to the pump and cross your fingers that your skimmer operates as well as it did before your cleaning. Do not be alarmed if your skimmer doesn’t immediately resume its former tuning after cleaning. With patience and experience, you will quickly learn that this is normal. You’ll also find that it is an excellent way to gain a better working knowledge of how this component works and how to fine-tune its performance. For larger skimmers, a spray bar or spout may be incorporated in the design to help rinse down the collection cup in between more involved and immersive cleanings.

In an established reef tank with an optimally functioning skimmer, you may find yourself cleaning out the collection cup two or more times a week. However, do not despair. On the scale of loathsome aquarium maintenance tasks, this one ranks pretty low and can actually be quite satisfying. Generally easy to do with a visually pleasing result.

Helpful tools and materials for cleaning your skimmer:

• Freshwater supply (RO/DI water or treated tap water)
• Magic eraser or other acrylic safe cleaning pad
• Silicone o-ring lubricant for conditioning any gaskets or o-rings, as needed. (It should be noted that only silicone o-ring lubricant may be used. Silicone products are not created equal and the wrong one may poison your system).

Components of the skimmer requiring regular maintenance:

• Collection cup and reaction chamber – wipe clean with an acrylic-safe cleaning tool.
• Pump – Periodically unplug, remove the volute, and clear the impeller of any built-up debris. Mag-driven pumps are fickle beasts. A little build-up or errant piece of sand trapped on or around the impeller can put the whole thing off balance and will greatly impact function. This could ultimately shorten the lifespan of this expensive piece of equipment. Plan to put pump maintenance on your calendar as an annual event, at least. Clean more frequently, if needed (listen for changes in sound from the pump – often clicking – as an indication that you may need to check the impeller).
• Venturi injector or Beckett device – Clear salt build-up from the air intake as needed. This can be accomplished by holding a cup of hot freshwater under the air intake. The hot water will be sucked in taking any salty build-up along with it. More airflow through the device will affect the amount and size of bubbles. Monitor your skimmer closely after clearing the air intake on your air injector.

DC Pumps and Protein Skimmers

DC (direct current) pumps are experiencing a bit of a moment on the aquarium scene. What’s all the hype about and should you buy into it? DC pumps offer an alternative to AC (alternating current – the type of power that comes out of a wall outlet) pumps and allow for more control and efficiency. The user can set the flow rate through the pump. For needle wheel injectors, this allows for greater control of bubble size and volume. Flow control also allows fine-tuning of skimmer water levels and contact time in the reaction chamber.

DC pumps also open up alternative skimmer management options to the user. Wet skimming is always a concern when running a protein skimmer. The best case for wet skimming is not removing any of the targeted waste from your tank. Worst case, if your skimmer collection cup is draining to a collection bucket or drain, you risk losing a lot of water from your system. With a DC pump your options for protecting against wet skimming increase. A drainage hose can be ditched and replaced with a float valve in the collection cup.

Downside? These pumps do tend to be more expensive than traditional AC pumps.

Conclusion

Protein skimmers are an indispensable filtration component for your reef aquarium. The amount of work they do for the amount of effort you put in is really quite astounding. Maintaining low nitrate levels is critical to maintaining a pristine reef tank. A protein skimmer is the tool you need to do just that. It can be a bit of work on the front end to figure out which skimmer style and type is right for your tank and to get it dialed in and functioning optimally. But, once you get your skimmer set up and running in that sweet, perfectly foamy spot, the results are worth the effort.