Why Protein Skimmers?

Protein skimmers are so critical that every saltwater aquarium must have one. The protein molecules that concern us here are the same proteins generated from dead algaes and corals, and regular metabolic behavior. The whole point of bio-filteration is to remove these protein molecules in the water. The proteins can be removed by algaes through their photosynthesis and bacteria through the denitrification process. However, nitrification (the second stage of the denitrification process) usually happens in a much faster rate then the denitrification process. That is, the tank produces more than it can clean up. So, there are generally more proteins in the water than these micro-organisms can handle. This introduces the need of the protein skimmer.

What a protein skimmer does in your tank is that it removes the protein molecules directly from your tank before they are taken care of by the bacteria. In other words, your protein skimmer can significantly reduce the amount of nitrogeneous molecules that bacteria in your tank must clean up. For this reason, we always recommend to our customers to get the best protein skimmer that you can afford because an efficient protein skimmer makes a very big difference in your tank.

Operating Principle and Comparing Performance with 6 Criteria

The operating principle of all protein skimmers involves three stages: generate fine air bubbles, allow the negatively charged protein molecules attached to the fine air bubbles in the reaction chamber, and collect the dry foam (the nitrogenous waste) in the collection cup. Based on this simple understanding, we can list 6 main criteria that you may consider when you are getting a new skimmer or when you are determining how efficient your skimmer is.

• Amount of Air Bubbles Produced - The functionality of your protein skimmer primarily depends on the effectiveness of the adsorption of protein molecules to the air water layers. The amount of air bubbles produced by your skimmer is one of the major parameters in protein skimming.

• Quality of Air Bubbles Produced - The quality of air bubbles produced means how fine the air bubbles are. When the protein molecules are attached to the air bubbles, a mono-molecular layer is formed. So the finer the air bubbles are, the more surface area for the protein molecules to be attached to in a given volume. Together the amount and the quality of the air bubbles produced represent only one thing - surface area for the protein molecules to be attached to. What we are saying here is that the more and the finer the air bubbles are, the better the skimmer is.

• Air - Water Contact Time - The second stage of protein skimming is to let the air bubbles to come into contact with the protein molecules. So the longer the time for the bubbles to come into contact with the protein molecules, the higher the probability for the protein molecules to be carried away. For this reason, we always want to have the maximal contact time. In fact, to ensure the skimmers to have their maximal air-water contact time, most of the skimmers manufactured use the same technique which is simply to have the water source (of the skimmer) near the bottom of the skimmer and so the air bubbles have the maximum amount of time to rise to the top of the reaction chamber.

• Efficiency of Dry Foam Collecting - Collecting dry foam is the last step in protein skimming. However, it is not as easy as it sounds. When the air bubbles have the protein molecules attached on them, the air bubbles will still be rising up to the top of the reaction chamber. However, only some of the air bubbles will be collected in the collection cup since the other air bubbles will be too heavy to be raised to the top. These bubbles are too heavy because they have water molecules also attached on them. As a result, the air bubbles that have the protein molecules attached and are finally collected are called the dry foam. Whereas the air bubbles that cannot reach to the top are called the wet foam. So collecting the dry foam affects the efficiency of the skimmer in that if the wet foam is also collected, the waste that you have collected in the collection cup is diluted. Therefore, for the same volume of waste that your skimmer has collected, you have less waste than it is supposed to be.

• Regular Maintenance of the Skimmer - The basic principle behind the protein skimmer is that the water surface must be electrically charged. However, if the food that you feed to your corals and fishes contains fat, the left-over food in the contact chamber is going to form a layer that can break the foam easily. This lowers the probability for the protein foam to be collected. For this reason, the contact chamber should be cleaned regularly.

• Gallon Handling Capacity - The number of gallons the protein skimmer can handle is always the first number that you look for when consider of getting a new skimmer. However, for North America products, their rated values are usually higher than what they are really capable of than the similar products manufactured in Europe. So if you are going to get a North American product, it is a wise decision to get one that has a capacity slightly bigger than the one you need. The gallon handling capacity also depends on how efficient your overall biological filteration system is. When in doubt, please check with your local dealer for a suitable capacity.

• Noise Level - All venturi protein skimmers make noise when they are operating. But some are particularly noisy. If you decide to have your tank in your office, you may not want to have a really noisy skimmer. This is particularly important when you are using a big skimmer for the obvious reason that the bigger the motor is, the larger the noise it produces.

Lee's Protein Skimmer

Here we have shown an inexpensive protein skimmer from Lee's Aquarium & Pet Products just to illustrate the basic principle described in the following discussion. Please click on the left picture to see the full size of it. The terms used in the following discussion correspond to the ones shown on the full size picture. The right picture is taken in our store. It shows the simple protein skimmer at work. The bubbles is formed in the contact chamber and the waste material is in the collection cup. The waste should be cleaned regularly.

A protein skimmer is basically a tube, called contact chamber, with a cup on the top to collect the waste which you must remove regularly. The contact chamber has an air stone sunk at the bottom and is a place where you normally see a lot of bubbles rising from the bottom of the chamber to the collection cup (see the right picture above.) The electrically charged amino- acids molecules adhere to the air bubbles, by which these charged molecules can be brought to the collection cup at the top. When the air bubbles reach the top of the foam riser tube, they come into contact with the air inside the collection cup, and hence, these bubbles form the foam that you see in the collection cup.

You may notice that not all the foam formed have the protein molecules adhered. You are right. There are two types of foam here: normal and protein foam. We only want the protein foam to be collected in the collection cup and the normal foam to be returned to the aquarium. The normal foam can be quickly broken up and to be returned through the return tube. They are easily recognized as the steam of bubbles of identical size going back to the aquarium. To see the bubble stream clearly. The waste that we want to remove is a brownish protein liquid (after settled) is called adsorbate.

If you want your skimmer to work at its peak efficiency, use air stones that can generate fine air bubbles. The finer the air bubbles are, the larger the probability for the protein molecules to be stuck on the bubbles. The air stone should also be kept at the bottom because this ensures that the air bubbles have the maximum amount of time to come into contact with the protein molecules. This again increases the probability for the protein molecules to be collected.

Lee's Performance

Now let us look at why this simple protein skimmer is not the optimal choice for a reasonably big, such as 90 Gallon, tank. The source of the air bubbles for this Lee's product is an air stone. Due to its very limited size, the amount of air bubbles produced is very limited also. Moreover, as the air stone has been used for a while, the air stone degrades. That is, algaes are formed on the surface of the air stone which reduces the surface area for the air stone and so the amount of air bubbles produced is going to decrease also. As the air stone degrades, we may also wonder if the quality of the air bubbles can maintain for its regular operation. The other drawback of this little skimmer is that there is a very small current flow into the chamber so that greasy material can easily build up on the inner surface of the contact chamber and these greasy material simply reduces the amount of air bubbles that can reach to the top of the chamber. (The greasy material refers to those left-over food discussed in the Regular Maintenance of the Skimmer criterion.) There is another obvious problem with this skimmer which relates to its efficiency of collecting the dry foam in the collection cup. However, for these 3 major reasons, we see that this skimmer is only good for small tanks or can only be used as supplement to a main system.

BIG MONBASA and Its Performance

On the left is another portein skimmer, Big Monbasa. The big Monbasa has a much higher gallon handling capacity than the simple Lee's product. Unlike the Lee's protein skimmer, the Big Monbasa skimmer is actually one of the venturi skimmers. That is, it does not use an air-stone to generate its air bubbles. It uses an external motor to mix and pump the air and water into the contact chamber.

When fully assembled, the Big Monbasa skimmer has a basket attached to the back of the skimmer. Inside the basket, there are 2 sections. One of the sections is where you put the venturi pump (for the incoming water) and the other section is where you put a soft rubber sponge (included) (for the out going water). The venturi pump included in the box is actually nothing more than a simple power head which allows you to pump water into the contact chamber. However, the pump also has an inlet for sucking air into the pump. When the pump is operating, the mixing of the air and the water, which occurs inside the pump, generates the air bubbles for the skimmer. For this reason, it generates a much higher volume of air bubbles than the simple Lee's skimmer.

The contact chamber has as inlet directed in such a way that when the water (together with the air bubbles) enters the contact chamber, the incoming water must be shooting downwards to the bottom of the chamber. This meets the requirement of allowing the maximal air-water contact time for the protein molecules to be attached on the air bubbles.

After the generation of the air bubbles, there is really not much of the difference in the second step of the process. The protein molecules get attached to the air bubbles. Air bubbles rise up to the top of the collection cup. Dry foam can then be collected. However, one of the advantanges of venturi pumps as compared to the Lee's product is that there is a good current flow into the chamber and so in general you do not worry about the greasy material built up on the inner surface of the contact chamber. This helps you to reduce to times to clean the inside of the skimmer, which can be painful since you need to shut off your system for a while (assuming that your system has a valve that allows you to block water entering the skimmer).

Another good thing about this product is that there is an exhaust pipe going back to the basket - the section that has a soft rubber sponge. This sponge can eliminate the excess air bubbles that have not been used up in the skimming process. If this sponge does not exist, you will see a lot of air bubbles pumping into the tank. This sponge takes care of this awkward situation. So you can connect the exhaust pipe directly back to the tank if you choose to do so.

However, the drawback of this skimmer is that this pump can be very noisy. This is actually a common question that you should always look into when purchasing a venturi pump. All venturi pumps operate on the same principle as vacuum cleaners. It sucks air into the pump and mix the air with water to produce the air bubbles. Because of this reason, this pump may not be suitable if you want your tank to be loacted in a quiet room.

Aqua Medic turboflotor 1000 ^multi

The next thing that we would like to introduce is a very common protein skimmer manufactured by the famous Aqua Medic Company. On the left, you see a picture of the Aqua Medic turboflotor 1000 unit. This protein skimmer has a few special features that have been patented by the Aqua Medic. We will look at these special features closely and compare them with the criteria listed above to show why this is a very popular unit.

The turboflotor unit is manufacturered in Germany and is capable of handling 125 to 250 Gallons. This unit, unlike the simple Lee's product shown before, has an external motor (the bottom left) to drive the water (and air) into the skimmer. That is, it is a venturi protein skimmer.

If fully assembled, the plastic pipe is to be connected between the motor and the grey nozzle, the inlet to the skimmer. Water will first enter the motor and then "processed" before entering the skimmer through the inlet. The motor has another inlet (not shown) for an air pump to be connected. Inside the motor, there is a needle wheel, one of the patented key features of the turboflotor. The needle wheel is driven by the motor and is constantly rotating. When the wheel is rotated, the rotation allows the air entering to the motor to dissolve into the current. The significance of the needle wheel is that rotating the wheel with many fine needles on it forces the water to go around the needles, and hence, more water surface is produced. This increase in water surface makes it very effective in generating fine air bubbles. This makes the skimmer work more efficiently than the simple Lee's skimmer. In fact, many American products try to duplicate this feature. But the difference is that their wheels are paddle wheels, not needle wheels. This makes a big difference in performance because the paddles do not force the water to go around them the way the needles do. Hence the paddle wheels do not give the fine air bubbles as the needle wheels do. This automatically gives a good rating on the quality of fine air bubbles to this Aqua Medic unit.

Remember that with the Lee's product, the fine air bubbles, the carrier of the waste, are generated by an air-stone. You can easily image that you will need a bunch of air stones to produce enough air bubbles once the skimmer exceeds a certain level of capability. So the simple skimmers that rely on air stones are only suitable for small tanks. This illustrates the absolute advantage of the venturi protein skimmers as compared to the air-stone skimmers. The venturi skimmers do a much better job than the simple air-stone skimmers in supplying the amount of air bubbles. Compared to the Big Mombasa, we say that the needle wheel is one of the features that makes the turboflotor 1000 unit a much better choice.

The turboflotor 1000 unit is a very popular equipment in our store. This and the following picture are taken from two of our different systems. The tank on the left is the same one that we use to demonstrate different lighting systems - Phase IV, Power Compact - on the MoreLighting page.

The collection cup has just been cleaned before this photo was taken. The collection cup should be cleaned regularly.

The following picture shows the whole setup of a Aqua Medic Reef 500 system. The Reef 500 is a complete biological filteration sytem and it includes a Turboflotor 1000 unit. If you are considering a biological filteration unit, this is really an excellent system. (We will talk about this system in the new page about Biological Filteration.)

Each of the 2 skimmers is placed inside a sump. Pay attention to the shape of the Foam Raiser Tube. You see that the Foam Raiser Tube, the tube inside the collection cup, has a unique shape. The Foam Raiser Tube has a shape of an inverted-cone.

This inverted-cone shaped Foam Rasier Tube is indeed another advantage of this product as compared to the other American products. In order for you to appreciate the significance of this special shaped foam raiser tube, you need to know a bit more of the types of foams that are produced inside the skimmer: normal and protein foam.

Normal foam is produced whenever water is being whirled up and aerated. They break up quickly and settle down easily. Do you see the foam in the middle of the Foam Raiser Tube? The top portion of the foam is brownish, but the bottom portion of foam is white. At the bottom of the foam raiser tube, the white foam is the normal foam. Above the normal foam is the brownish foam or the protein foam. We know that only the protein foam is what we want to collect.

The inverted-cone has such a shape that it reduces the surface area gradually as the foam reaches the top of the foam raiser tube. This increases the probability of the protein foam (also called the dry foam - because the foam is dehydrated) will reach the top and will be collected outside the Foam Raiser Tube. The way the protein foam to be collected is based on the fact that the heavier foam, the normal foam, will not make it to the top because of its weight. Gravity simply pulls the heavier wet foam back down. On the other hard, the dry foam, because of the electrically charged nature, can easily get attached on to the inner surface of the raiser tube. Once the dry foam gets attached, it can make its way up to the top of the raiser tube by constantly being pushed up by the upcoming dry foam. Once the dry foam reaches the top of the Foam Raiser Tube, the dry foam will be collected because the foam is not as heavy as than the wet foam (because of the water molecules). The dry foam will be collected in the volume outside the Foam Rasier Tube and inside the collection cup. So immediately we see that this skimmer is a lot more efficient than the simple Lee's product and the Big Mombasa. It handles most of the problem of sorting the dry foam from the wet foam. For these two features, the needle wheel and the inverted-cone shaped Foam Rasier Tube, we highly recommend this unit to people who are considering of upgrading their skimmers.

Note: It is this special feature of the Turboflotor 1000 unit inspires us to come up with the Dry Foam Collecting Efficiency criterion in order to compare different products. So you see the these criteria that we have listed here really comes from our daily experience and from our own experiments with different products. It is not hard to see and it is nothing but common sense.

Aqua Medic Turboflotor 5000 SHORTY

To the left is the Aqua Medic Turboflotor 5000 SHORTY. It is the latest member of the Aqua Medic Turboflotor family. It just arrived our shop about 1 week ago. Its operating principle is identical to the Aqua Medic Turboflotor 1000 product. However, this is much more powerful than the Turboflotor 1000 product. It handles 500 Gallons, whereas the 1000 model handles only up to 250 Gallons.

Compared to the Turboflotor 1000 products, this unit is almost 3 times as big as the 1000 unit. The external motor that mixes the air with the water is a lot more powerful than the one used by the 1000 unit. Perhaps more importantly, the collection cup of the Turboflotor 5000 SHORTY is a lot more bigger and longer then the 1000 unit. The bigger the collection cup, the more waste it holds. The longer the foam raiser tube, the better the dry foam collecting efficiency. As we have explained a minute ago, this is because it is now a lot more harder (the new foam raiser tube is now twice the length of the 1000 unit) for the wet foam to get to the top of the collection cup. This again is due to the fact that the wet foam is heavier than the dry foam. The gradual decrease in the opening of the raiser tube allows a much smaller chance for the wet foam to reach the top and hence boosts the product's efficiency.

You may also notice that this SHORTY unit has a much wider diameter than the 1000 unit. It is roughly 3 times wider than the 1000 unit. This may seem a bit strange at the first sight. Remember that we always want a maximal air - water contact time and so for most of the protein skimmers, the contact chamber is usually as long as the manufacturer can make. However, this SHORTY product goes in a slightly different direction in that instead of having a long tube, it has a much wider diameter. The wide diameter allows the air bubbles to spread out inside the contact chamber which compensates the shortening of chamber.

Note: You can see on this picture that there is also a small plastic air tube connecting to the motor. The motor uses this little tube to suck air in and generates the air bubbles.

Aqua Medic Turboflotor 5000 BABY

As far as this discussion goes, the Aqua Medic Turboflotor 5000 BABY is the best protein skimmer that we recommend to the advance people. This BABY is capable of handling 1000 Gallons or twice as much as the 5000 SHORTY.

The operating principle of this skimmer is identical to all the other Turboflotor members. But this is the best skimmer shown here because it has all the features of the 5000 SHORTY and it has one more. This 5000 BABY has the same diameter as the 5000 SHORTY, but twice as tall as the 5000 SHORTY. The 5000 SHORTY is only 2 feet tall and this 5000 BABY is 4 feet tall. This approximately doubles the air - water contact time of the 5000 SHORTY.

Note: The 5000 BABY shown is 4 feet tall. There is in fact another very similar product which is the 5000 Twin that is 8 feet tall. However, the 8 feet was sold on the same day it was shipped to our shop and so we cannot include a picture here.

3 Specific Maintenance Tips for Turboflotor Products

Since the Turboflotor family is such a popular item, we would like to discuss the 3 specific maintenance tips of this line of products.

• One thing that we have not mentioned in the regular maintainance is that you should clean the inner surface of the collection cup regularly. More specifically, it is the inner surface of the foam raiser tube that you should clean more frequenctly - we recommend that you should clean it every time you remove the waste in the collection cup. We mentioned earlier in the Lee's Performance section that they will be greasy material built on the inner surface of the contact chamber due to small current flow inside the Lee's contact chamber. So you can expect to have the same type of greasy material built on the inner surface of the raiser tube also due to small current flow (especially in the top half of the raiser tube). So by the same token, it is necessary for you to clean up the inner surface of the raiser tube just to make sure that there is no such greasy layer formed on the inner surface in order to have your skimmer working at its peak efficiency.

• Adjusting your water level of your skimmer is also a key factor in determining your skimmer's efficiency. Remember that we do not want a strong current to bring the wet foam up to the top of the raiser tube. In fact, for proper operation, the water level of your skimmer should be just below the bottom of the collection cup. That is, the water should just reach to the top of the contact chamber. Don't forget that the collection cup is not part of the contact chamber. It is a separate part of your skimmer. If you don't already know, there is one adjust knob installed to each of the outlets of your skimmer for you to adjust the water level. If you go back to the 5000 SHORTY picture, you see 2 grey plastic caps just above each of the outlets. These are the adjust knobs. The plastic knob is really nothing more than a small plastic pipe that has one single hole drilled in the middle of the pipe. By turning the knob, you can adjust the opening (of the hole) and this allows the amount of water going back to your sump. So if you fully open the holes (of both knobs) to the outlet, you have the maximum amount of water going back to the sump. The smaller you make the opening, the smaller the amount of water that can go back to the sump, and hence, more water can go to the top of the contact chamber. This raises your water level.

• We mentioned about the noise issue in the discussion of the Big Mombasa. We said that noise level is always an issue with venturi pumps. If you are considering of having a tank in your office, you can make use of the silencer part included in the Turboflotor 1000 unit. The silencer is to be installed to the air tube that the external pump uses for sucking air into the pump and mixes the air with water. This little silencer is very easy to install and indeed reduces the amount of noise produced by the external motor. Once you have killed this source of noise, the noise issue should not matter any more.