Protein skimmer

Details Protein skimmer Protein skimmer

2000-12-04

2002-08-20

Simmons, David A. (Department: 1724)

Liquid purification or separation

Processes

Making an insoluble substance or accreting suspended...

C210S905000, C210S776000, C210S167150, C210S416200, C119S264000

Reexamination Certificate

active

06436295

ABSTRACT:

The present invention relates to filter systems, and in particular to filter systems for salt and fresh water aquariums.
BACKGROUND OF THE INVENTION
Salt and fresh water aquariums are very popular and provide enjoyment for many people. However, maintenance of the necessary water quality in aquariums is a major challenge for aquarium owners. Protein skimmers are known and have proven to be somewhat effective in managing the water quality of aquariums. A protein skimmer is used to accomplish two key tasks when used in a marine water management system. A properly functioning protein skimmer effectively oxygenates water that passes through the body of the skimmer by introducing a large number of small air bubbles into the water. A protein skimmer also serves as a method for water purification by allowing the introduced air bubbles to react with the surrounding water molecules for a period of time, which enables pollutants to gather on the surfaces of the bubbles and become chemically attached. The bubble-water mixture is then separated, and the bubbles are directed out of the body of the skimmer and collected, with adhering pollutants, in a collection cup. This allows pollutants to be permanently removed from the water system.
There are several aspects that make some protein skimmers more effective than others. Overall water flow rate through the protein skimmer is important because the more water that is processed per unit time usually means that more pollutants are removed and more gas exchange occurs. The amount of contact time between air bubbles and water, and the quality of this contact time is important as well. If the bubbles are immediately withdrawn from the skimmer as soon as they are introduced, they may not be fully saturated with pollutants. Also, if the air bubbles react with the water in a laminar, non-turbulent fashion, contact between bubbles and pollutants is reduced. Therefore, there is a chance that the bubble may not become fully saturated with pollutants. In either case, maximum efficiency is compromised.
The number of air bubbles as well as their size, is also important. Having a larger number of bubbles increases the amount of pollutants that can be skimmed out through this air-water interaction. Numerous, small-sized bubbles afford greater surface area for this interaction than the same volume of larger-sized bubbles.
These are the most important, but not the only aspects of protein skimming which contribute to a given skimmer's efficiency and success. In general, the goal is to maximize the number and to minimize the size of the bubbles and to maximize the time the bubbles are in contact with the water.
Prior Art Skimmers
U.S. Pat. No. 5,554,280 discloses a protein skimmer known as a “Downdraft” skimmer. This design accomplishes efficient bubble generation by injecting a smooth-flowing, high-pressure stream of water through a long tube that contains special media designed to break apart and shred downwardly inducted air into froth. The tube containing the air shredding media is typically three to five times the height of the body of the skimmer, since shorter downdraft tubes holding smaller amounts of air-shredding media generally skim very inefficiently. This design critically relies on the presence of these air-shredding media for effective bubble generation. The main body of this design is a box whose main function is to separate the bubbles from the incoming water so that they can be gathered inside of a collection cup as dry foam. This type of protein skimmer is arguably the “best” and most efficient design available or known to aquarists currently. It does, however, possess several disadvantages. These are:
1. This design requires a very powerful water pump in order to make the “downdraft” tube work successfully. Without such a strong pump, bubble production is extremely limited.
2. The amount of bubble generation depends largely on the height of the downdraft tube, which means that this type of skimmer typically stands very tall—anywhere from nearly two to over five feet tall. Obviously, such a massive piece of filtration equipment is rather cumbersome and inconvenient for a home aquarium.
3. Though this design produces a large number of bubbles, the method of bubble generation does not produce for maximally efficient quality of air-water mixing. In other words, bubbles are produced as incoming water rushes down the downdraft tube, around the air-shredding media. The bubbles and water together flow cocurrently along side one another in a laminar fashion. Since turbulent, random mixing of water and air is restricted, potential efficiency is reduced. Furthermore, once the bubbles reach the end of the downdraft tube, they are very quickly separated from the water and directed into the foam riser assembly, which also limits contact time and skimming efficiency.
U.S. Pat. No. 5,122,267 discloses a “Venturi” protein skimmer. Venturi skimmers, unlike the previously mentioned design, operate by generating bubbles via the venturi effect. These types of skimmer require a special venturi valve apparatus and a very powerful water pump in order to be effective. In most designs, water is forced through a venturi valve into the bottom of the body of the skimmer, where the bubbles then rise up a long cylindrical column and form froth at the top. Most venturi designs accomplish only a small fraction of the amount of bubble generation, or frothy scum generation, of the previously described downdraft design.
U.S. Pat. No. 5,665,277 discloses a skimmer that generates bubbles through the use of a strong air pump which forces diffused air into the body of the skimmer directly. These types of skimmers are terribly limited since most air pumps cannot supply large-enough amounts of air to facilitate efficient skimming. These designs also require a separate water pump as well, which is rather inefficient.
Yet another method for bubble generation is described in U.S. Pat. No. 5,380,160. This type of skimmer utilizes the venturi effect, in combination with the bubble shredding effect that can be imparted by directing air through the impeller shaft of a spinning water pump. Because this design relies on the venturi effect, it suffers from the same pitfalls already mentioned.
Evaluating Prior Art Protein Skimmers
The efficiency of a given protein skimmer design is generally rated by either:
1. the quality/quantity of frothy scum produced, or
2. direct observation of the quality/quantity of bubbles produced per unit time.
With regards to the first criteria, production of small-sized bubbles is highly desirable (approximately 0.5 millimeters in diameter), since a given space filled with smaller bubbles offers greater overall air surface area that would larger bubbles. Generally, it follows that the more bubbles which are generated, the more pollutants which can be removed. Simply put, a good skimmer produces a large number of very small bubbles. Since most designs of protein skimmer feature transparent chambers or mixing columns, this factor can be easily rated.
With regards to the second criteria, the quality of frothy scum is usually rated by observing its color, thickness, and smell. A good quality scum is dark (coffee-like), paste-like in consistency, and smells rotten. A good skimmer produces large amounts of this type of scum.
Two diagnostic tests were performed in order to rate and determine the efficiency of the present invention against previously described models. Several control parameters were instituted in order to achieve consistency of data and to avoid the collection of incorrect information. All of the protein skimmers tested were collectively hooked up to a single, large marine aquarium filled with various live animals, and thus were “competing with one another” under the same exact environmental conditions. Each skimmer was operated according to manufacturer specifications. This test was performed continuously over the course of a two-week period, by which time each skimmer had stabilized and a very obvious hierarchy in skimmer efficiency was apparent. O

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