Part 4 The Filtration System
In this section I intend to present the filtration and circulation systems that maintains my show tank in a pristine clean condition for at least a month, without any intervention on my part. Information on how and why this system works will be presented later; for now I'm just going to specify the design of the system. The following list contains the key elements:
mechanical filter
purigen reactor
biological filter
tank water circulation
water exchange
Attention to detail is important in order to achieve the desired result. Thus, all of the elements in the list above must be accounted for and sized properly in order to handle the load. The load is ten adult discus in a 100 g tank. If the tank size or number of fish is different, the elements can be modified proportionally.
The picture below shows the mechanical filter, purigen reactor, biological filter, and circulation pump. For my application these items are housed in a basement closet located below the tank, thus eliminating noise and allowing easy access for servicing.
4-1 Filtration System:
Mechanical Filter-- Mechanical filtration is achieved with two 25 micron pleated cartridges. Each filter has 30 sq-ft of pleated material. Since there are two cartridges they provide 8460 sq-in of surface. This is normally a vary large filtration surface for a 100 gal tank, but all of it is necessary for the filtration system employed in my tank. Note that there is a pressure gauge mounted on the canister. This is very useful for determining when the filters need changing and cleaning. With my tank setup, the pressure gauge begins to indicate an increase about midway thru the fourth week after the last cleaning. The cartridges are then cleaned by placing them in a bucket of water using a weak solution of bleach, and they provide service for several years. The Nu-Clear canister is built like a tank (extremely rugged design), does not leak, and can be expanded with additional add-on modules.
A sump can be used to provide the same function providing it has sufficient means for trapping allot of material (equivalent to 60 sq ft or more). What I like about using a canister filter is that it is easy to service without adding a lot of debris to the aquarium, and the pressure gauge keeps tract of when it needs servicing.
Purigen Reactor-- My purigen reactor is a custom design and build. Here's a link that describes all of the details including how to service it:
This is one way of implementing a purigen reactor, but certainly not the only way. I have previously used a PhosBan 150 Reactor that I modified by adding two additional sponges and two mesh screens. Two of the sponges are placed at the top of the reactor. Sandwiched between the two sponges is a mesh screen that keeps the purigen out of the tank. A second set of sponges and mesh screen are placed at the bottom of the reactor. The two sponges hold the screen in place. This is a HOB type of setup and I use it for my QT tank. The screen material must be cut very carefully in order to keep the purigen beads out of the tank. PhosBan offers an optional pump for their reactor. However, I would recommend a pre-filter that operates in the 30 micron range in order to keep suspended material from clogging up the purigen reactor. A canister with a pleated filter and built in pump would work well for this pre-filter.
4-2 PhosBan Reactor:
There are other methods I have seen employed for a purigen reactor. Go to youtube.com and search "DIY Purigen Reactor" for lots of good ideas. As far as I know, no one markets a reactor specifically for purigen, and other reactors that are available will not work for purigen unless modified. Reference the link above for an explanation.
I use 250 ml of purigen, with a flow rate of 1.0 gal/min, for my 100 gal tank. A higher flow is not necessary and may cause the reactor to require servicing more often because it will eventually get plugged up. Purigen can be recharged using bleach and instructions are included with the product. Don't expect the 100 ml Media Bag to work. The bag material does not allow enough water contact to be effective.
Biological Filter-- The use of purigen greatly reduces the load placed on the biological filter and the reason for this will be explained in my next post. However, it is still absolutely necessary that a well established biological filter be present. I use a separate canister for this purpose because it allows me to pre-filter the water to 25 microns before entering the biological filter. That way I don't have to clean it often; in fact it can go at least 2 years without cleaning. I use 4 liters of SeaChen Matrix as the media.
Tank Water Circulation-- A large amount of water circulation is necessary to get good results; the reason for this will be explained later. Circulation is accomplished in two ways: the circulation pump, and the use of lift tubes. The picture below illustrates the how water circulates external to the tank.
4-3 External Circulation:
The Filter Pump transfers 1000 gal/hr. Since the tank is 100 gal, this means that the entire contents of the tank circulates thru the pleated canister filter 10 times each hour. Other features of the circulation system are the following:
1) New water is preheated by a separate 20 gal Pre-Heat tank.
2) The new water is mixed with the water entering the Filter Pump. This allows for good mixing.
3) Valves separately control the flow rate thru the Purigen Reactor and the Bio-Filter.
4) An overflow pipe assures that the automated water exchange system can never overfill the aquarium.
The following is a picture showing how circulation is controlled internal to the tank. Note the short PVC pipe with a cap on top and holes in it, located right where the water enters the aquarium. This pipe is located in the center of the tank and is hiden by the imitation tree stump. The stump is hollow and has been modified to allow water to exit around the bottom of it. Water is directed across the tank floor where the feces and uneaten food resides. The lift tube acts a water pump that draws water from the tank bottom and then transfers water to the top of the tank. The outlet of the lift tubes then direct the water towards the pipe that collects the feed water for the circulation pump. Do not assume that the water circulation pushes the feces and uneaten food into the water column, it does not work that way; this will be explained in my next post. Note that the following picture shows only the left hand side of the corner bow tank. There are three additional lift tubes on the right side.
4-4 Internal Circulation:
The filter pump and the lift tubes result in considerable circulation witin the tank, especially across the floor of the tank. This circulation is absolutely necessary to achieve the desired results for a pristine clean tank.
Circulation of water within the tank is also accomplished with the use of six bubble lift tubes. These are assembled from 1" thin wall tubbing and other components available on the internet.
4-5 Typical Bubble Lift Tube:
The lift tubes are driven by a Linear Piston Pump from Jehmeco, Model LPH45. This is by far the best air pump I have ever owned. The six lift tubes require allot of air and the Linear Piston Pump is very quiet and really does the job. Here's a link:
In this section I intend to present the filtration and circulation systems that maintains my show tank in a pristine clean condition for at least a month, without any intervention on my part. Information on how and why this system works will be presented later; for now I'm just going to specify the design of the system. The following list contains the key elements:
mechanical filter
purigen reactor
biological filter
tank water circulation
water exchange
Attention to detail is important in order to achieve the desired result. Thus, all of the elements in the list above must be accounted for and sized properly in order to handle the load. The load is ten adult discus in a 100 g tank. If the tank size or number of fish is different, the elements can be modified proportionally.
The picture below shows the mechanical filter, purigen reactor, biological filter, and circulation pump. For my application these items are housed in a basement closet located below the tank, thus eliminating noise and allowing easy access for servicing.
4-1 Filtration System:
Mechanical Filter-- Mechanical filtration is achieved with two 25 micron pleated cartridges. Each filter has 30 sq-ft of pleated material. Since there are two cartridges they provide 8460 sq-in of surface. This is normally a vary large filtration surface for a 100 gal tank, but all of it is necessary for the filtration system employed in my tank. Note that there is a pressure gauge mounted on the canister. This is very useful for determining when the filters need changing and cleaning. With my tank setup, the pressure gauge begins to indicate an increase about midway thru the fourth week after the last cleaning. The cartridges are then cleaned by placing them in a bucket of water using a weak solution of bleach, and they provide service for several years. The Nu-Clear canister is built like a tank (extremely rugged design), does not leak, and can be expanded with additional add-on modules.
A sump can be used to provide the same function providing it has sufficient means for trapping allot of material (equivalent to 60 sq ft or more). What I like about using a canister filter is that it is easy to service without adding a lot of debris to the aquarium, and the pressure gauge keeps tract of when it needs servicing.
Purigen Reactor-- My purigen reactor is a custom design and build. Here's a link that describes all of the details including how to service it:
This is one way of implementing a purigen reactor, but certainly not the only way. I have previously used a PhosBan 150 Reactor that I modified by adding two additional sponges and two mesh screens. Two of the sponges are placed at the top of the reactor. Sandwiched between the two sponges is a mesh screen that keeps the purigen out of the tank. A second set of sponges and mesh screen are placed at the bottom of the reactor. The two sponges hold the screen in place. This is a HOB type of setup and I use it for my QT tank. The screen material must be cut very carefully in order to keep the purigen beads out of the tank. PhosBan offers an optional pump for their reactor. However, I would recommend a pre-filter that operates in the 30 micron range in order to keep suspended material from clogging up the purigen reactor. A canister with a pleated filter and built in pump would work well for this pre-filter.
4-2 PhosBan Reactor:
There are other methods I have seen employed for a purigen reactor. Go to youtube.com and search "DIY Purigen Reactor" for lots of good ideas. As far as I know, no one markets a reactor specifically for purigen, and other reactors that are available will not work for purigen unless modified. Reference the link above for an explanation.
I use 250 ml of purigen, with a flow rate of 1.0 gal/min, for my 100 gal tank. A higher flow is not necessary and may cause the reactor to require servicing more often because it will eventually get plugged up. Purigen can be recharged using bleach and instructions are included with the product. Don't expect the 100 ml Media Bag to work. The bag material does not allow enough water contact to be effective.
Biological Filter-- The use of purigen greatly reduces the load placed on the biological filter and the reason for this will be explained in my next post. However, it is still absolutely necessary that a well established biological filter be present. I use a separate canister for this purpose because it allows me to pre-filter the water to 25 microns before entering the biological filter. That way I don't have to clean it often; in fact it can go at least 2 years without cleaning. I use 4 liters of SeaChen Matrix as the media.
Tank Water Circulation-- A large amount of water circulation is necessary to get good results; the reason for this will be explained later. Circulation is accomplished in two ways: the circulation pump, and the use of lift tubes. The picture below illustrates the how water circulates external to the tank.
4-3 External Circulation:
The Filter Pump transfers 1000 gal/hr. Since the tank is 100 gal, this means that the entire contents of the tank circulates thru the pleated canister filter 10 times each hour. Other features of the circulation system are the following:
1) New water is preheated by a separate 20 gal Pre-Heat tank.
2) The new water is mixed with the water entering the Filter Pump. This allows for good mixing.
3) Valves separately control the flow rate thru the Purigen Reactor and the Bio-Filter.
4) An overflow pipe assures that the automated water exchange system can never overfill the aquarium.
The following is a picture showing how circulation is controlled internal to the tank. Note the short PVC pipe with a cap on top and holes in it, located right where the water enters the aquarium. This pipe is located in the center of the tank and is hiden by the imitation tree stump. The stump is hollow and has been modified to allow water to exit around the bottom of it. Water is directed across the tank floor where the feces and uneaten food resides. The lift tube acts a water pump that draws water from the tank bottom and then transfers water to the top of the tank. The outlet of the lift tubes then direct the water towards the pipe that collects the feed water for the circulation pump. Do not assume that the water circulation pushes the feces and uneaten food into the water column, it does not work that way; this will be explained in my next post. Note that the following picture shows only the left hand side of the corner bow tank. There are three additional lift tubes on the right side.
4-4 Internal Circulation:
The filter pump and the lift tubes result in considerable circulation witin the tank, especially across the floor of the tank. This circulation is absolutely necessary to achieve the desired results for a pristine clean tank.
Circulation of water within the tank is also accomplished with the use of six bubble lift tubes. These are assembled from 1" thin wall tubbing and other components available on the internet.
4-5 Typical Bubble Lift Tube:
The lift tubes are driven by a Linear Piston Pump from Jehmeco, Model LPH45. This is by far the best air pump I have ever owned. The six lift tubes require allot of air and the Linear Piston Pump is very quiet and really does the job. Here's a link:
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