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I know from fishless cycling techniques (have yet to try it) that buying clear NH4+OH-  (according to wikipedia buying true Ammonium Hydroxide is impossible) and putting small doses will start the nitrogen cycle, but I'm wondering about it as a hydroponic technique. Now, I know this isn't bio-ponics ( I'm sure I can find a free source of NH2), but will this work with chemical salts too. I think I'll start experimenting sooner or later. 

Side note: this is how I'll dose my systems (sorry I'm a science nerd ):

Anyways, NH4+OH- will turn into nitrite and nitrate later via oxidization. The chemical equation for NH4 turning into Nitrite is as follows:

NH4 + 2O2 ----> 2H2O + NO2 

Turning Nitrite into Nitrate is as follows:

NO2 + O2------> H2O + NO3

Using stoichiometry we can test the ratio for how much we need. Say we want 40ppm of Nitrate. How much ammonia do we need. he equation is as follows.     You can stop here if it's dry

40ppmNitrate * 1mg/liter  * 1g   *   1molNitrate        *    1molNO21molNH418.03846g *1,000mg1ppm 

         1                1ppm   1,000mg  62.0049gNitrate     1molNO3    1molNO2       1mol        1gram     1mg/liter

                              =11.63679645ppmNH4 

(Did I do this right, I was introduced to the concept a few days ago?)

I can go back into the equation for the required amount for a 18gallon system. Anyways this is after cycling. 

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Replies to This Discussion

Hi Eric, 

I'm hoping one of the rocket scientists will be able to jump in here, as this is definitely out of my comfort zone. I'm pretty sloppy and can be a bit dyslexic which is a bad combination for this sort of thing :)  But I think that in your first equation ammonia is combined with oxygen and hydrogen carbonate to produce nitrates (and cell mass, and water, and carbonic acid).

Something like: NH4 + O2 + HCO3 ---> NO2 (and all that other stuff...H2O, H2CO3)

Then nitrite is combined with more oxygen, hydrogen carbonate, carbonic acid to produce nitrate, water, cell mass

NO2 + O2 + HCO3 + H2CO3 ---> NO3 (and cell mass, and H2O)

How much of each, I really don't know, ( I do know that to convert 1 'unit' of ammonia to nitrate you need over 4 times that amount of oxygen and about 8.5 times that amount of carbonate alkalinity, which is why AP systems need so much O2, and why the pH goes down over time).  

The stoichiometry I'm not even going to touch :))

Sorry if this wasn't much help...

I was't actually sure if I got the reactants and products right. I just assumed it was a combustion reaction, not unlike cellular respiration. I understand about the stoichiometry, it's just a way to see what you'll get and how much you'll need. Very helpful, thank you.

Vlad Jovanovic said:

Hi Eric, 

I'm hoping one of the rocket scientists will be able to jump in here, as this is definitely out of my comfort zone. I'm pretty sloppy and can be a bit dyslexic which is a bad combination for this sort of thing  But I think that in your first equation ammonia is combined with oxygen and hydrogen carbonate to produce nitrates (and cell mass, and water, and carbonic acid).

Something like: NH4 + O2 + HCO3 ---> NO2 (and all that other stuff...H2O, H2CO3)

Then nitrite is combined with more oxygen, hydrogen carbonate, carbonic acid to produce nitrate, water, cell mass

NO2 + O2 + HCO3 + H2CO3 ---> NO3 (and cell mass, and H2O)

How much of each, I really don't know, ( I do know that to convert 1 'unit' of ammonia to nitrate you need over 4 times that amount of oxygen and about 8.5 times that amount of carbonate alkalinity, which is why AP systems need so much O2, and why the pH goes down over time).  

The stoichiometry I'm not even going to touch)

Sorry if this wasn't much help...

maybe Rupert or one of the others with some chemistry knowledge can pop in here since I'm not up to correcting anyone's chemistry work.

You could provide the nitrogen this way but you will also have to provide all the other nutrients as well for good plant growth and then you are really just doing chemical hydroponics and will likely find yourself having to do nutrient change outs to keep things in balance and kinda miss out on the water savings you get from bio-ponics.

I don't think nutrient changes will be in order if I don't do Nitrate Salts, such as Calcium Nitrate, Potassium Nitrate, etc. . I'l just provide all the other minerals with organic sources. For example if I see Calcium deficiency I can add a little seashell and pH down to correct it. The pH down will correct Phosphorus. I also hope to do some worm castings. If I have enough Nitrate I'll dose less Ammonia. I'm trying to do a deconstructed pee-ponics system, as I don't think my family will get over the "yuck-factor".  
TCLynx said:

maybe Rupert or one of the others with some chemistry knowledge can pop in here since I'm not up to correcting anyone's chemistry work.

You could provide the nitrogen this way but you will also have to provide all the other nutrients as well for good plant growth and then you are really just doing chemical hydroponics and will likely find yourself having to do nutrient change outs to keep things in balance and kinda miss out on the water savings you get from bio-ponics.

Yes, I had I feeling I got the reaction wrong. What I'm doing is going through the reaction process and figuring out how much NH4 I'll need to produce xNO3. It's different than straight chemical salts hydroponics. Thank you. I'll find the reactants and products to produce a different result.

Peter Shaw said:

Aquaponics folks know that conversion NH4 to NO3 results in acidification, so we have to add bases to keep the pH from dropping so low,

so, dont forget the H+ that are generated.  NH4 will release 4H+

okay, how much fertilizer do you add? 

My favorite is this:

desired ppm/75/decimal fraction of the nutrient in the fertilizer = oz of fertilizer in 100 gal of water.

using NH4NO3 which is 34%N and picking 200 ppm N as the goal,.

200/75/.34 = 8 oz of NH4NO3 in 100 gal of water gives you 200 ppm N

OR

1ppm = 1mg/L

200 ppm N = 200mg N/L

but you need to know how much of the fertilizer is N, and using the same NH4NO3 

only 34 percent of the 200 mg/L is N so...

.34/200 = 588 mg NH4NO3 / L of water give you 200 ppm N

 

Eric, see if you can work on the 'yuck factor', if not (depending on what you plan to grow) you could always just use the nitrates, P and the bit of K steeped from the worm castings. K can be added with wood ashes. Plant usable Calcium (depending on your water), you'll get when you add any acid like your pH down to your water. Mg also from your water (depending) Rusty nail filings (10 grams per 4 or 5 gallons of water should be good, gypsum will have Sulfur as well as Calcium...That should take care of your primary and secondary nutes. A bit of sea water or maxi crop should take care of your trace elements...

Precipitates will usually build up as mainly Calcium phosphate and Calcium sulphate over time (it looks like a light grey-ish sludge). Zinc, Copper, Iron, and Manganese will aslo tend to 'stick' to this sludge. This precipitate sludge can actually be used to you advantage if managed properly, and will keep you from having to add those nutrients separately.



Eric Warwick said:

I don't think nutrient changes will be in order if I don't do Nitrate Salts, such as Calcium Nitrate, Potassium Nitrate, etc. . I'l just provide all the other minerals with organic sources. For example if I see Calcium deficiency I can add a little seashell and pH down to correct it. The pH down will correct Phosphorus. I also hope to do some worm castings. If I have enough Nitrate I'll dose less Ammonia. I'm trying to do a deconstructed pee-ponics system, as I don't think my family will get over the "yuck-factor".  
TCLynx said:

maybe Rupert or one of the others with some chemistry knowledge can pop in here since I'm not up to correcting anyone's chemistry work.

You could provide the nitrogen this way but you will also have to provide all the other nutrients as well for good plant growth and then you are really just doing chemical hydroponics and will likely find yourself having to do nutrient change outs to keep things in balance and kinda miss out on the water savings you get from bio-ponics.

These are the real chemical equations.

2NH4+ + 3O2------> 4H+ + 2H2O + NO2-
2NO2-  + O2---------> 2NO3-

This works after establishing a biofilter, by the way. I don't think I'll do the one for hydrogen ions, it's getting late.So, I'm going to attempt to use stoichiometry for testing how much we need.  Ok, 40ppm of Nitrate. 

40ppmNitrate 1mg/liter  * 1g   *   1molNitrate        *    2molNO2 * 2molNH4 * 18.03846g *1,000mg * 1ppm    =23.27359289ppmNH4

         1                1ppm   1,000mg  62.0049gNitrate     2molNO3    1molNO2       1mol        1gram     1mg/liter


                                                                   



Eric Warwick said:

I don't think nutrient changes will be in order if I don't do Nitrate Salts, such as Calcium Nitrate, Potassium Nitrate, etc. . I'l just provide all the other minerals with organic sources. For example if I see Calcium deficiency I can add a little seashell and pH down to correct it. The pH down will correct Phosphorus.

 

Well it may.... if it is Phosphoric acid... but many pH Down products aren't...

 

And there's an inter-relationship between phosporus and calcium... that I'm too tired to post now... but basically high phosphorus can lock out calcium....

 

And the importance of phosphorus is greatly exaggerated IMO...

 

 

If I have enough Nitrate I'll dose less Ammonia.

 

Not sure what you might use to dose with.... and I (kind of) understand your "aversion" to chemical nitrates....

 

But in terms of plants... ammonia/ammonium... is taken up by plant roots in early growth stages...but latter stages actually require transport of nitrates to the leaves, where via photsynthesis... the majority of a plants life cycle occurs...

 

If you going to run the system with chemical input of ammonia... then you might just as well use chemical nitrates....

 

Basically ala hydroponics.... if you wishing to run ala "organic hydroponics".... then a combination of worm casting, seaweed extract... and judicious (small) doses of urea.. will suffice...


RupertofOZ said:"If you going to run the system with chemical input of ammonia... then you might just as well use chemical nitrates...." The point was to create a nitrogen cycle. Basically all that is inorganic would be the NH4. I may be missing the point, however.

 

I'm going to dose with straight Ammonia to create a nitrogen cycle.


RupertofOZ said:

"But in terms of plants... ammonia/ammonium... is taken up by plant roots in early growth stages...but latter stages actually require transport of nitrates to the leaves, where via photsynthesis... the majority of a plants life cycle occurs..." Yeah, I recently read Hydroponic Food Production, apparently it's also good for high light levels. 

RupertofOZ said: Basically ala hydroponics.... if you wishing to run ala "organic hydroponics".... then a combination of worm casting, seaweed extract... and judicious (small) doses of urea.. will suffice...

I'm trying to run something a little different. I think nutrients are over-priced and I want to make my own. Well, my family won''t let me make it directly.

RupertofOZ said:

Well it may.... if it is Phosphoric acid... but many pH Down products aren't...

 

And there's an inter-relationship between phosporus and calcium... that I'm too tired to post now... but basically high phosphorus can lock out calcium....

 

And the importance of phosphorus is greatly exaggerated IMO...

 

 

If I have enough Nitrate I'll dose less Ammonia.

 

Not sure what you might use to dose with.... and I (kind of) understand your "aversion" to chemical nitrates....

 

But in terms of plants... ammonia/ammonium... is taken up by plant roots in early growth stages...but latter stages actually require transport of nitrates to the leaves, where via photsynthesis... the majority of a plants life cycle occurs...

 

If you going to run the system with chemical input of ammonia... then you might just as well use chemical nitrates....

 

Basically ala hydroponics.... if you wishing to run ala "organic hydroponics".... then a combination of worm casting, seaweed extract... and judicious (small) doses of urea.. will suffice...

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