What is Foam Fractionation, and how does it work?

Foam Fractionation or Protein Skimming is the removal of proteins, dissolved organics, and total suspended solids from water. Unlike other forms of mechanical filtration that only trap debris and waste, Foam Fractionation or Protein Skimming, actually removes or strips it from the water.

This process is carried out inside of a Foam Fractionator or Protein Skimmer by injecting air, in the form of tiny bubbles, through a column of water creating an air to water interface. In general, the smaller the bubbles the more effective the foam fractionation or protein skimming process is. This is because smaller bubbles have more surface area while occupying the same volume of water as larger bubbles. This mixture of air and water is injected towards the bottom of the Foam Fractionator or Protein Skimmer and allowed to travel up through the incoming organic laden water. Due to the natural charges of these organic molecules, they are either repelled or attracted to the air/water interface. These molecules can be described as hydrophobic. Large numbers of small bubbles present an enormous air/water interface for molecules to collect on the bubble surface (the air/water interface). This process continues until the bubbles increase near the top of the water column inside the foam fractionator or protein skimmer, they become denser and the water begins to drain and create the foam that will carry the organic molecules to the waste collection cup and the organic molecules will be exported from the water.

Why Use a Foam Fractionator or Protein Skimmer?

Adding a Foam Fractionator or Protein Skimmer has many benefits. Most systems that employ a Foam Fractionator or Protein Skimmer are on a closed filtration loop with either little or no introduction of new water. With the exception of normal water changes there is very little waste removal. Overtime uneaten foods, fish waste, and other dissolved organics can build up to dangerous levels. Foam Fractionators and Protein Skimmers can remove the waste before it is able to reach dangerous levels. This will help decrease the number of water changes needed in the system. The foam fractionation or protein skimming process will also increases water clarity and dissolved oxygen concentration. Consequently, appetite, stocking densities, feed and growth rates are all enhanced and animal health improved.

Used within aquaculture, animal rehabilitation, live seafood holding as well as most public aquariums worldwide, foam fractionators and protein skimmers are an essential component within any aquatic life support system. Foam fractionation is effective in seawater, freshwater as well as brackish water systems.

What Makes RK2 the #1 Selling Foam Fractionator/Protein Skimmer in the World?

RK2 Systems has been the leading manufacturer of foam fractionators and protein skimmers for the last 25 years. What makes RK2 the number one selling foam fractionator in the world is our endless commitment to enhancing products through research and development, our design, and the materials we use in production.

A. Design

RK2 Foam Fractionators and Protein Skimmers have been designed to carry out the Foam Fractionation process in the most efficient way possible. This is achieved by utilizing two methods; longer contact times and a design that employs counter current exchange. Contact time is defined by the volume of water inside the fractionator body and the flow rate through it. Countercurrent exchange is a design that allows “dirty” water to enter the top of the fractionator body and exit down through the bottom. As the dirty water is passing down through the body it is stripped of organics by the bubbles being injected into the bottom, which rises to the top to begin forming foam. It is important to note that it is not about introducing as much air as possible but rather the optimal air to water ratio and the size of the bubbles being injected. This is crucial for maintaining the best possible air to water interface. Air flow meters are standard equipment on all RK2 Foam Fractionators and Protein Skimmers to monitor the performance of each injector. If the air flow drops, it’s an indication that the Fractionator’s or Skimmer’s air intake assembly needs to be cleaned. Many of our competitors fail to realize the importance of the details mentioned above. In most cases, other manufacturers don’t even know how much air is being introduced into their protein skimmers and are sizing their pumps in an effort to maximize the amount of air they can introduce into their units rather than achieving optimal air to water ratios.

To keep the injector pumps as efficient as possible we have worked directly with our pump manufacturer, Multi Duty Manufacturing (MDM Inc) to optimize the process. Each injector pump is precisely sized to each fractionator model to ensure optimal air to water ratios all while using the most energy efficient motors possible.

B. Materials

RK2 Foam Fractionators and Protein Skimmer bodies are made from ozone resistant High Density Polyethylene (HDPE). Unlike others that are plastic welded together with unsightly weld marks, RK2 Fractionator bodies are a rotationally molded, once piece design. Through this design we are able to offer a safer and more durable solution when compared to other suppliers that utilize bodies with multiple joints and welds that are potential failure or break points. Our collection cups and riser cones are made from cell cast acrylic. All hardware associated with our foam fractionators and protein skimmers are 316 stainless steel designed for corrosive environments. Even our pumps are provided.

False or Misleading Claims and Unsupported Statements

False or Misleading Claims and Unsupported Statements

Some manufacturers may lead you on with false/misleading claims and make statements that can’t be supported through empirical data/evidence. Statements such as “substantial power savings over comparable models” or “unmatched, superior performance” without showing the data is audacious. Looking at full load amps and running amp draw is simple and can be done by just about anyone to show if there is truly a power savings. Do not allow a “used car salesman” approach from any manufacturer to cause confusion as to what is important design criteria (contact time, power consumption, air draw) versus what is irrelevant (self-absorbed statements without factual data shown).

Undersized “Equivalent” Models

Another example you may come across is the combination of under sizing or over rating of the Protein Fractionator/ Protein Skimmer. As an example, “Company A” offers a model that is 60” in diameter with a recommended flow rate of 600GPM at 2 minutes of contact. “Company B” offers a 48” diameter model for 550GPM with unspecified contact time while stating it is “equivalent” to the 60” model. Volume Metrics will tell you that a 48” diameter and 60” diameter model with approximately the same height cannot hold the same volume of water. Therefore if the flow rates are nearly the same, the 48” model has SIGNIFICANTLY LESS contact time. How is the smaller unit “equivalent” to the larger? Sizing this way results in an undersized fractionator. Company B’s model continuously foams and is “constantly” pulling waste, while Company A’s model has peaks and valleys in foam production. Company B will spin this by saying their model works better and produces more foam than Company A. What is happening is Company A’s model has caught up and removed the waste from the system. Therefore foam production will “rest” until there is enough waste to start foaming again. Meanwhile, Company B’s model constantly foams because it cannot keep up with the waste being produced due to being undersized.

When comparing different Protein Fractionators and Protein Skimmers ask for hard, factual data. If the answer to your questions are “that’s not important” or “that’s proprietary information” that company may be keeping truthful answers from you. Ask for more substantiated, empirical proof. RK2 Foam Fractionators and Protein Skimmers are relied upon across the world. With 25 years of experience, constant research and development, high quality components and craftsmanship, RK2 Foam Fractionators and Protein Skimmers cannot be beaten!

When looking for a protein fractionator/protein skimmer there are many things to consider.

  1. Overall Design and functionality - What Type of Protein Fractionator/ Protein Skimmer are you purchasing? How are the air/bubbles introduced into the water? What is the contact times using the manufacturer’s recommended flow rates?
  2. Overall Capital Cost - Upfront Purchase Price of the equipment.
  3. Cost of Ownership - One of the most overlooked aspects of purchasing new equipment. How much does it cost to operate? Electrical costs, replacement part costs, etc.
  4. Materials and Manufacturing Process - What material is the unit made from and how is it made?
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