Nitrogen Cycle for a Fishless Pond


tbendl

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Could someone explain the nitrogen cycle for a pond with no fish. I don't understand how I am getting green water and understand even less how to combat it so I thought I'd check the basics first.
 
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Maybe frogs? Dead leaves? I don't know. How to fight it - empty it out and refill. No fish no problem.

I just wanted to chime in because I miss your witty banter around here.
 

Meyer Jordan

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Could someone explain the nitrogen cycle for a pond with no fish. I don't understand how I am getting green water and understand even less how to combat it so I thought I'd check the basics first.

In a pond without fish, there are less factors influencing the Nitrogen cycle than would be if fish were present, but it is still functioning. All organic matter, when it decomposes, gives off Ammonia as a by-product. Some more than others. The nitrifying bacteria transform this ultimately to Nitrate which is used by algae to fix (eat) Carbon. Algae also have the ability to take up Ammonia directly by assimilation where it is internally converted to Nitrate.
If you are getting green water in a Water Garden (no fish) then it is because of an elevated presence of Ammonia and/or Nitrate. If it were string algae then it would be Ammonia and/or Phosphorus. In either case, you have decaying organic matter.
 
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In a pond without fish, there are less factors influencing the Nitrogen cycle than would be if fish were present, but it is still functioning. All organic matter, when it decomposes, gives off Ammonia as a by-product. Some more than others. The nitrifying bacteria transform this ultimately to Nitrate which is used by algae to fix (eat) Carbon. Algae also have the ability to take up Ammonia directly by assimilation where it is internally converted to Nitrate.
If you are getting green water in a Water Garden (no fish) then it is because of an elevated presence of Ammonia and/or Nitrate. If it were string algae then it would be Ammonia and/or Phosphorus. In either case, you have decaying organic matter.
Agreed

Dave
 

tbendl

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Thank you Meyer, everything I had pulled up on the web had fish as the producer of ammonia. I guess I should probably get my water tested to see if it's ammonia or nitrate and then go from there. The pond was recently drained and cleaned and I have been scooping regularly and am not getting any decaying leaves or plant matter off the bottom. Is there a chance it is coming from the bog and there just isn't enough filter (ie plant matter) to take up the nitrate? And if that's the case, would an additional bio filter or additional plants help? Aeration or additional water movement?
I appreciate the response from you both!
 

Meyer Jordan

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Thank you Meyer, everything I had pulled up on the web had fish as the producer of ammonia. I guess I should probably get my water tested to see if it's ammonia or nitrate and then go from there. The pond was recently drained and cleaned and I have been scooping regularly and am not getting any decaying leaves or plant matter off the bottom. Is there a chance it is coming from the bog and there just isn't enough filter (ie plant matter) to take up the nitrate? And if that's the case, would an additional bio filter or additional plants help? Aeration or additional water movement?
I appreciate the response from you both!

Could possibly be your 'bog' as they do trap organic matter. When did you last clean it? A biofilter will only convert the Ammonia into Nitrate so you will still have the problem. More plants will help.
 
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tbendl

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I started my pond and bog last August/September time frame. Will aeration or water movement also help with algae? I've read differing views on this.
 

Meyer Jordan

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Aeration may help. Do not place it close to Waterlilies if you have any. Waterlilies do not like a lot of water movement.
 
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