Biofilter

[Juan Carlos Narbon]

I world like to know how a Biofilter work in a system and if you could share a design for making it myself.

[Leo White Bear]

Juan-

  There are many various types of biofilters.  The type and design really depends on the design of your aquaponic system in so much on its effectiveness.  Do you have a system that has tubes or channels where the plants grow out of pots?  Is your system a media based system, meaning that you have grow beds filled with gravel, hydroton, rocks or lava rocks?Is your system design verticle such as zip tower configuration?  According to Dr. Wilson Lennard, design affects the whole system.

  Now that we got that out of the way, just a bucket filled with gravel and plumbed between your grow area and the fish tank will work for a time.  My biofilter is plumbed between my 10 gallon fish tank and consists of a small plastic rectangular trash can filled with gravel.  I have a 4 pound plastic peanut butter jar, with a hole large enough in the lid so the plug and the inlet hose to my media-based grow bed fits through going to their respectable points.  With holes drilled into the jar, it is burried in the NOW biofilter and covered with 1/2" - 3/4" gravel.

  The aquarium is plumbed with a "U" siphon to the biofilter over the edge of the aquarium.  As long as the "U" siphon is totally filled with water and the ends are submerged it works very well.  I have no idea how efficient this is but it will work until Spring and the weather warms up.  I hope this helps.

White Bear

[Cameron Smith]

"Biofilter" is the term used to describe the nitrogen cycle in your system or the "cycle" or "cycling". It's called the biofilter because it is composed of biological elements--the nitrifying bacteria that convert ammonia to nitrites and nitrites to nitrates. Because these bacteria convert waste products that are harmful to fish (the ammonia in the system resulting from fish breathing, peeing, and pooping and from the breakdown of excess fish food) into a product which is a desirable input for plants, they are said to "filter" the water "bio"logically. There isn't actually any mechanical filtration of the water taking place the way we typically think of an air filter or water filter working.

You "construct" a biofilter by baiting these beneficial bacteria, which exist naturally in the air around us, to your system and encouraging them to colonize. You do this by adding ammonia to the system. You can either allow the fish to constantly add small amounts of ammonia to the system just by eating and breathing, or you can add ammonia to the system yourself using a number of different techniques Sylvia teaches in her excellent book, Aquaponic Gardening. A word of warning: do not attempt to add ammonia to your system manually if you have fish in your system. They will add plenty by themselves, and adding more without sufficient biofiltration in place will be likely to kill them. When it comes to cycling, less is more. You can't bully the bacteria into growing faster. You can add gravel or water from a fully cycled system to jumpstart the system, but you will never be able to change the rate of growth of the bacteria.

If you were thinking more along the lines of a mechanical filtration system to remove solids from your system, the gravel in your grow bed will accomplish this for you.

[Bob Terrell]

Juan

Now that you know what a bio filter is, check youtube.  There are many vidios of different bio filters that people have built. I am sure you will find one to suit your needs.

[Juan Carlos Narbon]

Thanks  you all.  My system is made of rafts floating on water, and I figured that I needed some sort of filtering for the solids coming from the FT.  Now it is clear to me that the biofilter helps in doing this and also in having a place for the bacteria to develop.

 

I´ll check youtube for designs.

 

Thanks.

[Juan Carlos Narbon]

One more question.  After there is some build up of solid in the filter, is it required to remove it?

 
Juan Carlos Narbon said:

Thanks  you all.  My system is made of rafts floating on water, and I figured that I needed some sort of filtering for the solids coming from the FT.  Now it is clear to me that the biofilter helps in doing this and also in having a place for the bacteria to develop.

 

I´ll check youtube for designs.

 

Thanks.

[Harold Sukhbir]

Hi Juan,

For filtering solids

http://www.earthangroup.com.au/diy-backyard-budget-swirl-filter/

[Bob Terrell]

yes, you will have some build up of solids and how often you clean it depends on the style you build and the flow rate.  And don't forget to get red worms for your system.
 
Juan Carlos Narbon said:

One more question.  After there is some build up of solid in the filter, is it required to remove it?

 
Juan Carlos Narbon said:

Thanks  you all.  My system is made of rafts floating on water, and I figured that I needed some sort of filtering for the solids coming from the FT.  Now it is clear to me that the biofilter helps in doing this and also in having a place for the bacteria to develop.

 

I´ll check youtube for designs.

 

Thanks.

[Juan Carlos Narbon]

Can red worms live under water?

[Bob Terrell]

yes, but put them in your grow beds.  oh, I see you have a raft system, hmmmmmm   I guess they would live in a raft system??????   Anybody.........

[Harold Sukhbir]

Hi Juan,

I have made a swirl filter with netting inside (combination filter). The red worms started to live in the submerged netting. The raft was connected to media beds.

[Leo White Bear]

Cameron-

  I disagree with the statement "Biofilter" is the term used to describe the nitrogen cycle in your system"  This is in referance to "BIOFILM, the bacteria that grows in the biofilter.  You were very eloquant in describing the cycling process but, various system designs do not have a grow bed setup such as the NFT  design hense a BIOFILTER must be constructed to house the bacteria to convert the ammonia to nitrites and a seperate species of bacteria to convert these nitrites into nitrates that the plants utilize for their growth.  A BIOFILTER is a unit either where the plants grow in proper, or a seperate design construct that the bacteria grow in. 

  I believe that Juan was refering to the mechanical removal of fish wastes solids from the system (especially since his design is if floating raft design).  No initial media bed involved to act as the biofilter.

White Bear
 
Cameron Smith said:

"Biofilter" is the term used to describe the nitrogen cycle in your system or the "cycle" or "cycling". It's called the biofilter because it is composed of biological elements--the nitrifying bacteria that convert ammonia to nitrites and nitrites to nitrates. Because these bacteria convert waste products that are harmful to fish (the ammonia in the system resulting from fish breathing, peeing, and pooping and from the breakdown of excess fish food) into a product which is a desirable input for plants, they are said to "filter" the water "bio"logically. There isn't actually any mechanical filtration of the water taking place the way we typically think of an air filter or water filter working.

You "construct" a biofilter by baiting these beneficial bacteria, which exist naturally in the air around us, to your system and encouraging them to colonize. You do this by adding ammonia to the system. You can either allow the fish to constantly add small amounts of ammonia to the system just by eating and breathing, or you can add ammonia to the system yourself using a number of different techniques Sylvia teaches in her excellent book, Aquaponic Gardening. A word of warning: do not attempt to add ammonia to your system manually if you have fish in your system. They will add plenty by themselves, and adding more without sufficient biofiltration in place will be likely to kill them. When it comes to cycling, less is more. You can't bully the bacteria into growing faster. You can add gravel or water from a fully cycled system to jumpstart the system, but you will never be able to change the rate of growth of the bacteria.

If you were thinking more along the lines of a mechanical filtration system to remove solids from your system, the gravel in your grow bed will accomplish this for you.

[Harold Sukhbir]

Hi Juan.

So, from the discussion this far, my guess is that you are seeing the difference between bio filtration and mechanical filtration. In raft systems the ratios between fish, raft, and plants are calculated to meet the bio-filtration demands of a particular system. So no add-on bio-filtration becomes necessary. Mechanical filtration may not be necessary if the system has low fish/feeding loads. If however, fish/feeding loads are at higher ratios you can employ mechanical filtration utilizing a clarifier or swirl filter or similar, to effectively remove solids and lower the nitrogen loading in a system. In my system i designed a combination biological and mechanical filter, which worked effectively for my raft, which is an option you may also want to consider. The simpler alternative would be to attach a swirl filter between the FT and raft bed. The solids in the filter can be removed, at intervals, to regulate the nitrogen for healthy fish and maximum plant growth.