Nitrification

[Bob Campbell]

Here is a detailed description of nitrification.  Recently it was asked what happened to the Nitrate.  I too wondered about this.  This video will explain that phenomenon.   Bottom line for aquaponics is lots of air because we want the Nitrate. 

Click This Link.or watch this

[Chris George]

Interesting video Bob.....loved it when the little 'nitrifiers' keeled over when the PH was wrong....

[RupertofOZ]

Be careful extrapolating to much from the video... yes it's a good explaination of the entire nitrogen cycle...

 

But aspects of anoxic "denitrification"... are neither encourage.. or normally exist in aquaponics...

 

The answer as to where the nitrates go.. in aquaponics.... the answer is ... your plants use it...

[Robert Rowe]

Thank you Bob Campbell - Sure glad you stuck to the Basics. I remember now why I chose the Physical Sciences over the Chemical. I think my guess was pretty good and much easier on my brain.

[Bob Campbell]

What happens to the Nitrate when there are no plants?

RupertofOZ said:

Be careful extrapolating to much from the video... yes it's a good explaination of the entire nitrogen cycle...

 

But aspects of anoxic "denitrification"... are neither encourage.. or normally exist in aquaponics...

 

The answer as to where the nitrates go.. in aquaponics.... the answer is ... your plants use it...

[RupertofOZ]

It would continue to build up... ultimately, although high levels are required, to the detrement of fish...

But why would you have an aquaponics system... without plants... it wouldn't be an aquaponics system...

It would be essentially an aquaculture system... in which case you would be employing aquacultural techniques to remove solids.. and bio-filtration...

[Bob Campbell]

The question of where did the Nitrates go came about from a situation where there were no plants in the system.  Tests indicated that Nitrates were present the gay before but gone the next day.  I too have seen this happen.

RupertofOZ said:

It would continue to build up... ultimately, although high levels are required, to the detrement of fish...

But why would you have an aquaponics system... without plants... it wouldn't be an aquaponics system...

It would be essentially an aquaculture system... in which case you would be employing aquacultural techniques to remove solids.. and bio-filtration...

[Jon Parr]

Bob, are you just wondering why the nitrates disappeared in a system with no plants? As long as aeration is good throughout the system, nitrates should build if not being used. If no plants are using them, and nitrates diminish, then anaerobic zones are converting it to atmospheric nitrogen. It's as simple as that unless I'm missing something. Great video.

Why the concern with nitrates? On other threads of yours it seems paramount in your thinking. I'm pretty sure you're the only one out there adding urea to boost nitrate. Have you ever had a nitrogen deficiency in AP? It's pretty rare, and a surplus of nitrogen is only good for leafy greens, or veg state on flowering plants. After that, it's best to cut back on the N to improve the yield. My local college grows hydro tomatoes, and they are constantly changing the recipe according to the growth stage of the plant, and the results are dramatic. The early plant recipe has high N, and the growth is truly phenomenal. The new tip growth erupts with a fist of crinkled leaves, like they can't grow fast enough. Seriously, it's like steroids. But if they kept that up, the jungle of plants would never produce. So they tweak the formula, lower N, and the toms take a more traditional look and throw blossoms and fruit. They even increase the EC during ripening, effectively dehydrating the plant, in order to get the flavor in the toms.

Anyway, why the concern over N? :)

[Bob Campbell]

@Jon Parr - Why the concern with nitrates?

I like many others are still raising our first batch of fish and don't have enough in the system to create sufficient Nitrates.  Until the fish grow larger and eat more food, I am supplementing the ammonia. 

I'm still learning and may be way off track.  I've only had two crops, but I noticed a big different in my indoor duckweed tank after I began to keep a little excess Nitrate going, and I'm pleased with the results I had this summer in the outdoor system too.

In my mind the optimum balance would be just a hair above zero where the plants are consuming the Nitrate at the same rate it's being produced.  But until I began supplementing the readings were always zero.  I realized there is no nutrient value in urea, but it would be too expensive to throw excess food in.

[Jon Parr]

Thanks, Bob. I wouldn't say you are off-track. I'm not against adding urea at all, in fact I'm not against pure hydro. Ultimately plants simply need nutrients, and chemical nutes are really the same elements and compounds as those supplied by the fish. Other forms of bio-ponics are equally fascinating.

Other than duckweed, has there been any evidence of N def? Or any comparable boost in growth from urea supplementation? Whether I read nitrates or not, I have never seen a lack of N in AP, which certainly may be luck on my part, IDK. And to be honest, I'm almost always overstocked with fish load. However, even with no fish at all, plants don't seem to notice for at least a month, sometimes more. Other than humonia, urea, and extra fish food, you might consider throwing in some veg waste like prunings and clippings, mown grass, bags of leaves, that sort of thing, to boost N along with other nutes.

[Bob Campbell]

@Jon Parr - Other than humonia, urea, and extra fish food, you might consider throwing in some veg waste like prunings and clippings, mown grass, bags of leaves, that sort of thing, to boost N along with other nutes.

That's a pretty good idea.   Someday I'll set up a small fishless aquarium and bio filter to test that idea.  I think I have heard of people using paint strainer bags full of compost too do something similar.