Aquaponic Biofilter – 10 of the Many Benefits to using them

aquaponic biofiltration

An aquaponic biofilter does the very same thing as it does in aquaculture and as the name suggests it uses biololgicals, specifically bacteria to convert the fish wastes into plant food (ammonia to nitrate).  In aquaponics we want as much nitrate as we can get and really have no need for ammonia to grow plants, so having a simple biological filter makes great sense.  My preference is for moving beds or trickle filters or even a combination of both.

  1. Convert the fish wastes into perfect plant food.  Most plants don’t like ammonia, the biofilter does the heavy lifting for you and provides the plants with what they need – Nitrate!
  2. Take the guess work out of systems biological needs provided you know how much feed you put in.
  3. Helps reduce the oxygen demand on the system (particularly aerated moving bed bio filters and if solids are removed).
  4. A moving bed filter helps keep the Carbon Dioxide under control.  Even though most aquaponics run at low pH and low alkalinity, this is still very important should you raise either one.
  5. Very inexpensive and easy to build.  Can be as little as $100 which will save you $$$ in dead fish…
  6. With the right bio media they can be 8 times smaller than a grow bed required for the same job
  7. They don’t require cleaning to keep them working at their peak
  8. Require next to no maintenance.  They just keep ticking alone regardless of what you do with your plants in the media bed.  You can remove plants all you like without disturbing the “balance” in the system.
  9. Gives you the means to isolate the plants from the fish should you need to.  This is often required if you need to clean your growbeds out or heavily treat the fish with salt, something your plants don’t like.
  10. Very little loss of precious Nitrogen to the atmosphere.  When your media bed gets too much nasty in it, it continues to complete the nitrogen cycle and converts the Nitrogen in your system to Gas and it is gone!

Aquaponic biofilter use is a very simple process that many already understand - the nitrogen cycle.  Most beginners start out in aquaponics with their fish tank and just use their media grow beds to do the solid and biological filtration. As I noted in the article “5 Reasons why Filtration Works in Aquaponics” this works very well but it has its limits.

The “limits” in aquaponics are no different to recirculating aquaculture.  The primary limits to aquaculture and therefore aquaponics are driven ONLY by the amount of feed you put into the system and are as follows:

  • Oxygen
  • Ammonia
  • Suspended Solids
  • Carbon Dioxide

- See more at: http://www.earthangroup.com.au/flow-rates-are-critical-in-aquaculture-systems/

If any of the above reaches limits beyond your aquaponic systems capacity to produce or process, it will fail resulting in dead fish first and to a latter extent poor plant growth.

aquaponic-biofilter-earthangroupAquaponic biofilter limits

An aquaponic biofilter with some form of solids filtration before it will help you control three of these limiting factors, Oxygen, Ammonia and Carbon Dioxide.  If a bio filter manages 3 out of 4  in aquaponic systems from the fish feed you put in, it is clear they are a very important consideration in your designs, backyard or commercial.

The oxygen limit in a biofilter; aquaculture or aquaponic biofilter, is driven by the nitrifying bacteria need for oxygen to oxidize (catabolize) ammonia to nitrite to nitrate.  From a basic chemistry point of view it looks like this NH4+NH3 (Total Ammonia) from the fish then NO2 and on to NO3.  You can see the Oxygen being added to each compound through the nitrogen cycle.  So you need oxygen to do this.  You don’t need much but more is better to help speed the process up.

In an aquaponic biofilter, especially a moving bed has both the capacity to supply sufficient oxygen for the bacteria and at the same time help remove Carbon Dioxide (CO2).  Something a media bed will not do.  In fact a media bed adds considerably to both of these issues.

A final word on bio filtration in Aquaponics. “Just because you think or someone says you don’t need one, does not mean you, your fish and your plants won’t benefit from having one.  The fact as I have shown you, is they will as will your table at dinner time.”

Regards
Paul

An aquaponic biofilter does the very same thing as it does in aquaculture and as the name suggests it uses biololgicals, specifically bacteria to convert the fish wastes into plant food (ammonia to nitrate).  In aquaponics we want as much nitrate as we can get and really have no need for ammonia to grow plants, so having a simple biological filter makes great sense.  My preference is for moving beds or trickle filters or even a combination of both.

  1. Convert the fish wastes into perfect plant food.  Most plants don’t like ammonia, the biofilter does the heavy lifting for you and provides the plants with what they need – Nitrate!
  2. Take the guess work out of systems biological needs provided you know how much feed you put in.
  3. Helps reduce the oxygen demand on the system (particularly aerated moving bed bio filters and if solids are removed).
  4. A moving bed filter helps keep the Carbon Dioxide under control.  Even though most aquaponics run at low pH and low alkalinity, this is still very important should you raise either one.
  5. Very inexpensive and easy to build.  Can be as little as $100 which will save you $$$ in dead fish…
  6. With the right bio media they can be 8 times smaller than a grow bed required for the same job
  7. They don’t require cleaning to keep them working at their peak
  8. Require next to no maintenance.  They just keep ticking alone regardless of what you do with your plants in the media bed.  You can remove plants all you like without disturbing the “balance” in the system.
  9. Gives you the means to isolate the plants from the fish should you need to.  This is often required if you need to clean your growbeds out or heavily treat the fish with salt, something your plants don’t like.
  10. Very little loss of precious Nitrogen to the atmosphere.  When your media bed gets too much nasty in it, it continues to complete the nitrogen cycle and converts the Nitrogen in your system to Gas and it is gone!

Aquaponic biofilter use is a very simple process that many already understand - the nitrogen cycle.  Most beginners start out in aquaponics with their fish tank and just use their media grow beds to do the solid and biological filtration. As I noted in the article “5 Reasons why Filtration Works in Aquaponics” this works very well but it has its limits.

The “limits” in aquaponics are no different to recirculating aquaculture.  The primary limits to aquaculture and therefore aquaponics are driven ONLY by the amount of feed you put into the system and are as follows:

  • Oxygen
  • Ammonia
  • Suspended Solids
  • Carbon Dioxide

- See more at: http://www.earthangroup.com.au/flow-rates-are-critical-in-aquaculture-systems/

If any of the above reaches limits beyond your aquaponic systems capacity to produce or process, it will fail resulting in dead fish first and to a latter extent poor plant growth.

aquaponic-biofilter-earthangroupAquaponic biofilter limits

An aquaponic biofilter with some form of solids filtration before it will help you control three of these limiting factors, Oxygen, Ammonia and Carbon Dioxide.  If a bio filter manages 3 out of 4  in aquaponic systems from the fish feed you put in, it is clear they are a very important consideration in your designs, backyard or commercial.

The oxygen limit in a biofilter; aquaculture or aquaponic biofilter, is driven by the nitrifying bacteria need for oxygen to oxidize (catabolize) ammonia to nitrite to nitrate.  From a basic chemistry point of view it looks like this NH4+NH3 (Total Ammonia) from the fish then NO2 and on to NO3.  You can see the Oxygen being added to each compound through the nitrogen cycle.  So you need oxygen to do this.  You don’t need much but more is better to help speed the process up.

In an aquaponic biofilter, especially a moving bed has both the capacity to supply sufficient oxygen for the bacteria and at the same time help remove Carbon Dioxide (CO2).  Something a media bed will not do.  In fact a media bed adds considerably to both of these issues.

A final word on bio filtration in Aquaponics. “Just because you think or someone says you don’t need one, does not mean you, your fish and your plants won’t benefit from having one.  The fact as I have shown you, is they will as will your table at dinner time.”

Regards
Paul

About the author

Paul Van der Werf

Paul is the Operations Manager for a 4400m2 integrated aquaculture pilot project in the United Arab Emirates desert he designed and built. This is a commercial aquaponics pilot to evaluate integrated farming in arid climates.

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9 Comments on “Aquaponic Biofilter – 10 of the Many Benefits to using them

  1. BensonGapuz

    Thank you Paul for being generous in sharing what you know.

    Reply
  2. steve

    Really like all the good stuff you are doing. Where can I find more info on building the biofiltration system?

    Reply
    1. Check out my youtube channel “EarthanGroupFilms”

      Reply
  3. Trevor

    Paul could you please explain point 10 a bit more please, especially converting nitrogen to gas
    Cheers Mate

    Reply
  4. Pingback: Adding Biofiltration : Aquaponics for Aquarists

  5. Bernard Fiocchi

    Hi

    1. How much air do I have to give to a Bio-filter.. are is it not destroying the structure of the waste??
    So where exactly do I give air? in the Bio-tank? midsection??
    2. Air lifter.. how much air does it give the water?
    3. Worms.. in Media-beds???? would they eat organic waste like dead roots … I will try it.. no worry

    I thank you

    Feel free to look at facebook where I post my pics of the Roof Aquaponics project

    Reply
    1. about 1 liter per minute per 20 liters of biofilter
      airlift will give it to saturation in the pipe
      no point really preference to do the worms elsewhere
    2. Reply

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