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Part 4 is divided into three sections. The first section discusses the basic philosophy of what is involved in designing a Purigen Reactor and how the design addresses these issues. The second section presents the reactor design and includes a parts list and pictures on how it is constructed. The third section presents the method of servicing the reactor with pictures.
SECTION 1 - Design Considerations
The design of a reactor for Purigen starts by understanding the make-up of the Purigen material.
Characteristics of Purigen - Size. The Purigen beads are very small, about 0.030 inch in diameter. They are made small because this creates the maximum surface area. But this creates the problem that they can become compacted unless water flows upward thru them. When water flows thru them properly, the beads are said to be fluidized. But there is another problem with tiny beads: they can easily clog a filter.
Characteristics of Purigen - Density. The Purigen beads are just SLIGHTLY more dense than water. (A small fraction of them are less dense than water and will float.) When water flows upward thru them, they will be thrust upwards, depending on the flow rate of the water. Thus a filter is necessary to keep the tiny beads from being carried into the aquarium. The beads are not harmful to the fish, but a tank full of tiny beads is not pleasing to the eye. The problem here is that the filter has to be sized properly so that it will operate sufficiently long with out getting plugged up with the tiny beads.
The Challenge of Designing a Purigen Reactor. The challenge is to build a reactor that will fluidize the tiny beads properly, keep the beads out of the aquarium, provide a sufficient flow rate to accomplish the intended purpose, accommodate sufficient Purigen, and operate continuously for at least a month without requiring servicing. Servicing will be necessary to either replace the Purigen, or clean the filter due to clogging by the tiny beads, whichever occurs first. The design presented addresses each of these issues. Note "design presented" refers to my design.
Amount of Purigen Necessary. My results indicate that 250 ml of new Purigen in the presented design is sufficient to provide filtration for 10 adult discus in a 100 g tank for at least one month. (I would guess that it might go for 6 weeks.) SeaChem claims that the effectiveness of Purigen is decreased about 10% each time it is regenerated.
Flow Rate Thru Purigen. My results indicate that a flow rate of 0.5 to 1.0 gallon per minute in the presented design is sufficient to provide filtration for 10 adult discus in a 100 g tank. After measuring actual flow rate, and observing how high the Purigen beads "boil", future flow rate can then be estimated; thus, this can be used to indicate when the filter is becomming clogged.
Getting the Reactor to Fluidize the Purigen Properly. In the design presented, water enters the vessel chamber at the bottom, and then flows up thru the baffle, and then the Purigen Platform. The baffle and Purigen Platform reduces water turbulence and presents even flow up thru the Purigen beads. Uneven water flow thru the Purigen would cause some beads to be thrust up higher than others. The higher the beads are lifted, the more likely they will be traped in the filter.
Filter Size. The design presented permits use of a large pleated filter. The greater the filter area, the longer it will operate without clogging. If a sponge was used to accomplish this, it would probably not provide sufficient filtration area.
Separation Between the Top Surface of the Purigen and The Filter. The greater the separation, the longer the filter will operate without clogging. The design presented permits a separation distance between 6 and 14 inches. (6 in to the bottom of the filter and 14 in to the top.) Close observation of the filter shows that the bottom of the filter becomes clogged first. Results with the design presented indicate that the filter will operate for at least a month without clogging, providing that the valve which regulates flow rate is turned on gradually. Thus, care must me taken when increasing the flow rate or the service life of the filter will be reduced. After removal and cleaning, the filter can be reused many times.
SECTION 2 - Purigen Reactor Design and Construction.
There are probably many ways to design a Purigen Reactor. My attempt here is by no means the only way, or not necessarily the best way to do it. But it does provide sufficient contact with the Purigen beads to provide the results claimed in Part 1, and it will work for at least one month without cleaning. Someone will come along and improve on the design, or perhaps come up with an entirely different approach. In the meantime the design presented will provide good service.
The following link contains a parts list, where the parts may be obtained, a list of assembly details, how water flows thru the reactor, and assembly and sub-assembly details.
Final Construction Detail. Now comes the interesting part of the building process: how to get the internal parts to fit properly when the cap is in place and tightned. This is accomplished by the "fit and try" method. First, remove all internal parts in the reactor except for those attached to the cap. Lubricate the reactor vessel O-ring, place the cap on the vessel and tighten the cap until it is snug (do not over tighten). Then scripe two marks, one on the cap and one on the vessel to indicate when the cap is on properly and seated.
Second, refer to picture #3 in the link above that shows the Upper Internal Assembly. The length of the CPVC pipe (part 8) should be adjusted so that the filter is slightly compressed when parts 6 and 7 are brought together.
Third, place the Lower Internal Assembly in the reactor vessel and press firmly in place as shown in picture #11.
Fourth, place the Upper Internal Assembly and Cap on/into the vessel and begin to rotate the cap. When some resistance is felt, note how much material needs to removed from parts 5 (PVC Slip coupling) in order to get the cap to seat properly on the reactor vessel. Remove the Cap, dissemble the Lower Internal Assembly and remove material from any or all of the slip couplings (part 5). Continue this process until the filter is slightly compressed and the two o-rings on the Upper Internal Assembly are seated properly and the two scribe marks in the first step above line up. This takes a little time and patience, but be sure to do the job right, otherwise water will not flow properly thru the reactor.
SECTION 3 Purigen Reactor Servicing
The method of servicing the reactor is shown in the link below. It takes about 20 minutes to accomplish.
Controlling Purigen During Servicing. Handling Purigen presents no problem at all. To transfer from one container to another, stirr and pour. To separate or rinse Purigen, let the beads settle (takes about a minute) and pour off excess water.
SECTION 1 - Design Considerations
The design of a reactor for Purigen starts by understanding the make-up of the Purigen material.
Characteristics of Purigen - Size. The Purigen beads are very small, about 0.030 inch in diameter. They are made small because this creates the maximum surface area. But this creates the problem that they can become compacted unless water flows upward thru them. When water flows thru them properly, the beads are said to be fluidized. But there is another problem with tiny beads: they can easily clog a filter.
Characteristics of Purigen - Density. The Purigen beads are just SLIGHTLY more dense than water. (A small fraction of them are less dense than water and will float.) When water flows upward thru them, they will be thrust upwards, depending on the flow rate of the water. Thus a filter is necessary to keep the tiny beads from being carried into the aquarium. The beads are not harmful to the fish, but a tank full of tiny beads is not pleasing to the eye. The problem here is that the filter has to be sized properly so that it will operate sufficiently long with out getting plugged up with the tiny beads.
The Challenge of Designing a Purigen Reactor. The challenge is to build a reactor that will fluidize the tiny beads properly, keep the beads out of the aquarium, provide a sufficient flow rate to accomplish the intended purpose, accommodate sufficient Purigen, and operate continuously for at least a month without requiring servicing. Servicing will be necessary to either replace the Purigen, or clean the filter due to clogging by the tiny beads, whichever occurs first. The design presented addresses each of these issues. Note "design presented" refers to my design.
Amount of Purigen Necessary. My results indicate that 250 ml of new Purigen in the presented design is sufficient to provide filtration for 10 adult discus in a 100 g tank for at least one month. (I would guess that it might go for 6 weeks.) SeaChem claims that the effectiveness of Purigen is decreased about 10% each time it is regenerated.
Flow Rate Thru Purigen. My results indicate that a flow rate of 0.5 to 1.0 gallon per minute in the presented design is sufficient to provide filtration for 10 adult discus in a 100 g tank. After measuring actual flow rate, and observing how high the Purigen beads "boil", future flow rate can then be estimated; thus, this can be used to indicate when the filter is becomming clogged.
Getting the Reactor to Fluidize the Purigen Properly. In the design presented, water enters the vessel chamber at the bottom, and then flows up thru the baffle, and then the Purigen Platform. The baffle and Purigen Platform reduces water turbulence and presents even flow up thru the Purigen beads. Uneven water flow thru the Purigen would cause some beads to be thrust up higher than others. The higher the beads are lifted, the more likely they will be traped in the filter.
Filter Size. The design presented permits use of a large pleated filter. The greater the filter area, the longer it will operate without clogging. If a sponge was used to accomplish this, it would probably not provide sufficient filtration area.
Separation Between the Top Surface of the Purigen and The Filter. The greater the separation, the longer the filter will operate without clogging. The design presented permits a separation distance between 6 and 14 inches. (6 in to the bottom of the filter and 14 in to the top.) Close observation of the filter shows that the bottom of the filter becomes clogged first. Results with the design presented indicate that the filter will operate for at least a month without clogging, providing that the valve which regulates flow rate is turned on gradually. Thus, care must me taken when increasing the flow rate or the service life of the filter will be reduced. After removal and cleaning, the filter can be reused many times.
SECTION 2 - Purigen Reactor Design and Construction.
There are probably many ways to design a Purigen Reactor. My attempt here is by no means the only way, or not necessarily the best way to do it. But it does provide sufficient contact with the Purigen beads to provide the results claimed in Part 1, and it will work for at least one month without cleaning. Someone will come along and improve on the design, or perhaps come up with an entirely different approach. In the meantime the design presented will provide good service.
The following link contains a parts list, where the parts may be obtained, a list of assembly details, how water flows thru the reactor, and assembly and sub-assembly details.
Final Construction Detail. Now comes the interesting part of the building process: how to get the internal parts to fit properly when the cap is in place and tightned. This is accomplished by the "fit and try" method. First, remove all internal parts in the reactor except for those attached to the cap. Lubricate the reactor vessel O-ring, place the cap on the vessel and tighten the cap until it is snug (do not over tighten). Then scripe two marks, one on the cap and one on the vessel to indicate when the cap is on properly and seated.
Second, refer to picture #3 in the link above that shows the Upper Internal Assembly. The length of the CPVC pipe (part 8) should be adjusted so that the filter is slightly compressed when parts 6 and 7 are brought together.
Third, place the Lower Internal Assembly in the reactor vessel and press firmly in place as shown in picture #11.
Fourth, place the Upper Internal Assembly and Cap on/into the vessel and begin to rotate the cap. When some resistance is felt, note how much material needs to removed from parts 5 (PVC Slip coupling) in order to get the cap to seat properly on the reactor vessel. Remove the Cap, dissemble the Lower Internal Assembly and remove material from any or all of the slip couplings (part 5). Continue this process until the filter is slightly compressed and the two o-rings on the Upper Internal Assembly are seated properly and the two scribe marks in the first step above line up. This takes a little time and patience, but be sure to do the job right, otherwise water will not flow properly thru the reactor.
SECTION 3 Purigen Reactor Servicing
The method of servicing the reactor is shown in the link below. It takes about 20 minutes to accomplish.
Controlling Purigen During Servicing. Handling Purigen presents no problem at all. To transfer from one container to another, stirr and pour. To separate or rinse Purigen, let the beads settle (takes about a minute) and pour off excess water.
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