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13.2 PROTEIN SKIMMERS:

13.2.1 INTRODUCTION:

Whether you use a protein skimmer of the columnar or of the venturi type, and whether you use it with or without ozone, is a matter of how much you want to improve your water quality. My experience has taught me that you must use one, if you want to improve that water quality. There is no way around it, except running a largely understocked tank with an oversized filter.

Although the use of protein skimming has greatly increased in the last year or two, many hobbyists still feel that such filtration may not really be required, or that they can get away with a real small unit. Such is not my experience, and such is also not the experience of recognized German authors such as G. Hueckstedt, P. Wilkens, Sander and Lemkemeyer.

Protein skimmers work on the principle that if small air bubbles are chased forcefully through a column of water, they will pick up organic and other material as they rise, and create a strong foam that contains all the matter they have picked up. Removing that foam removes the matter, and since it is no longer part of the system, it cannot break down and stress the filtration and the animals in the tank. Just looking at what comes out of a well operated skimmer should convince even the skeptics.

13.2.2 TYPES OF SKIMMERS:

Two types are commonly available in the hobby: columnar skimmers and venturi skimmers (also called power skimmers). Columnar skimmers are more widespread and therefore more familiar. They are less expensive to make, especially when certain of the parts are molded, as is the case in some of Route 4 Marine Technology's units, and of the of Sander ones.

Foam fractionation, as it is called in an industry where such filters emanated from, has been around for decades and is nothing new or fancy, just an efficient way to remove certain compounds from water.

The problem the hobbyist must deal with when deciding on the purchase of a skimmer is not only which type (columnar or venturi), but the size and the quality of the unit. This is especially so if ozone is to be used.

The photograph shows both a columnar and a venturi skimmer. It should be obvious that venturi skimmers are much smaller and can, therefore, be placed underneath the aquarium, in the cabinet.

Venturi skimmers operate on exactly the same principle as columnar ones, but differ in the manner in which the air is mixed with the water. Rather than using a rather crude wooden air diffuser approach, specially made valves, manufactured manually or molded, are used to generate extremely small bubbles very forcefully, much more forcefully, and in larger quantities than is possible with air stones. Because of this improvement in bubble size, bubble quantity and mixing, the units can be much smaller. And since space underneath a tank is always at a premium...

Being able to hide the skimmer from view is one advantage of venturi skimmers, but the additional efficiency is much more appealing. Better efficiency means better water quality, means a better looking aquarium. TAT builds venturi skimmers into all their trickle filters, making that filter perhaps the best buy on the market, because you get not only one of the best filters, but for the same price you get a venturi skimmer as well. And since stand alone venturi skimmers can cost $500, you may want to think about this carefully if you are in the market for a filter.

Whereas columnar skimmers require a fair amount of adjustment, venturi skimmers usually do not. You set them up and regulate the water flow and the foam height, and you are skimming without having to readjust the levels ever so often. This, too, is an advantage to consider and factor into your decision.

Venturi skimmers with molded venturi valves are more efficient than venturi skimmers with manually made venturis, but your system may not need the higher efficiency of the molded venturi if it is only stocked at medium level and operated with a good trickle filter. Talk to the manufacturer and then decide which one is better for you. The difference in price is worth the time.

With any skimmer, but especially with venturi skimmers, make sure that you can operate them with a great deal of ozone if that is what you have in mind for your system. Not all can.

13.2.3 OPERATING THE SKIMMER:

After installing your unit, operate it with a pump, or a by-pass from the main water return line, and adjust the flow rate to equal about 1 to 1.5 times the amount of water in your system. If you do not have a flow meter you will have to gauge this somewhat. The amount of water you push through the skimmer is not extremely critical, but enough must go through for all the water to be skimmed in a regular fashion. Many hobbyists flow greater amounts of water through their skimmers and report better results. Experiment a little until you have it set right.

In fact, if you own a redox potential controller or meter you can measure the redox of the outflowing water at various speeds and decide on which one is best. That would obviously be the setting you would want to select.

Venturi skimmers typically require more water flow because of the venturi valve. The more forcefully you push water through the valve assembly, the more forcefully you will draw in air, and the better skimming levels you will attain. On the venturi skimmer in the photograph 600 gallons per hour is a minimum, but what an effect.

Because ozone changes the consistency of the foam that develops at the top of the skimmer, levels and foam must be adjusted each time you make a change in the amount of ozone that is injected. This applies to all skimmers. Observe the levels when you make the change and readjust if necessary. Sometimes changes in water and foam levels take time to become apparent. Do not walk away from a skimmer unless you are sure that the level is not changing. This may take 10 to 15 minutes to be visible.

Air stones wear out quickly, especially if used with a lot of ozone, and the bubbles they produce will rapidly increase in size. This reduces the efficiency of the skimming process a great deal. Your air stone(s) need to be replaced when this happens. Make it a point to do so. There is no sense spending money on a skimmer and then not operating it the way it should be operated.

If ozone is injected into the skimmer, use ozone resistant tubing to connect the output of the ozonizer to the air/ozone mix input on the skimmer. Not doing so reduces the amount of ozone that is actually available for the skimming process. Norprene* is the recommended tubing. Silicone tubing will last for a while, and polysulfone is the best but also the most expensive, fetching as much as $8.00 a foot retail for the very high grade quality.

If ozone can be smelled in the room where the skimmer is placed, suspect that it is coming out of the top of your columnar skimmer, or that you have a leak in the ozone line. The former is more often than not the explanation though. To prevent this from continuing, install an ozone cap on the top of your skimmer. This is a round cup, of the same diameter as the top of the skimmer, with a perforated bottom, and filled with activated carbon. All air/ozone coming out of the skimming column must now go through the carbon before it can escape into the free air. Since carbon neutralizes ozone your problem should be solved.

Clean the top cup of your skimmer regularly. This will allow you to better determine where the foam level is and it will also reduce odors that may otherwise emanate from the scum that collects in the cup. Alternatively, make a connection with a small diameter hose from the skimmer cup, to a larger container with a lid, placed on the floor. Scum will now flow from the top to that container, and the lid will prevent odors from getting into the surrounding air. You will have to make a small hole through the lid to pass the hose through. Make it tight. Some companies, for example, Route 4 Marine Technology and Marine Technical Concepts, offer special containers to do just that.

Certain additives can make your skimmer foam much more forcefully than normal, usually because they contain binders or colloids, or both. To prevent the skimmer from overflowing, test a small amount of any new additive you plan to use and make sure it does not affect the way your skimmer operates. Be especially careful of KH generating compounds, some vitamins, some nutrient elements, and a number of others. This does not mean that you cannot use them, but you must add them only in very small quantities. In the case of KH generators this is not practical, and I suggest you get yourself one that does not affect your skimmer.

Skimmers are meant to run 24 hours a day. I see no reason why you shouldn't. When a time comes that little is to be removed from the water, the skimmer will not produce as much foam. That's all. When later on, e.g. after feeding, or when algae die, and they do all the time, more organic matter will be present in the water, and the skimmer will start removing it again. Do not be misled, a skimmer that has been running for a while may not have anything to remove from the water, so it won't. Such does not mean that your skimmer is not working properly. It probably is.

Once you have adjusted your protein skimmer properly, leave it alone. The more you adjust, the more readjusting you will have to do, and the more unnecessary work you are creating for yourself. Note that this applies to both columnar and venturi skimmers.

Small Reef Aquarium Basics, and a few issues of Marine Reef, the newsletter we publish go into even more detail on skimmers and outlines a chart on how to size your protein skimmer accurately. You may wish to refer to them if you need still more information.

Two volumes of back issues of Marine Reef now exist. Volume one, Year one includes issues 1 through 17, and Volume two, Year two includes all issues from 18 through 34. Both are available form Aardvark Press for $30.00 each, or for $50.00 if you order both of them. To keep yourself up-to-date on what is happening in the hobby, and to learn more about the requirements of the animals you keep, consider subscribing to the newsletter. It will be a worthwhile investment.

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