Is nitrate dosing effective

undermind

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Is there a difference between nitrate from fish waste and nitrates that were directly dosed when it comes to coral metabolism?
Well you raise a really good question and I've often wondered the same thing.

In my current tank I've struggled to keep my nitrates up at a level I want, and I've dosed nitrates off and on. My opinion unfortunately doesn't prove anything but I've always felt that nitrate dosing satisfies a number on my test kits but that's mainly it.

To put it another way, I've maintained a nitrate of 10 by dosing sodium nitrate, and I've maintained 10 by feeding consistently heavier. The latter produced a tank with better coral growth and health. Obviously there are different factors at play with these two routes.

Hopefully this thread can raise some good discussion.
 
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gbroadbridge

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Just curious what makes you choose potassium nitrate over sodium nitrate. I had been using potassium nitrate but I started to worry about potassium levels increasing so I switched.
Actually, I prefer Calcium Nitrate over Potassium Nitrate, however something consumes quite a lot of Potassium in my tank so if a test shows it under 380 at the same time as I need to dose Nitrate, that's the bottle I reach for :)

I have a lot of KNO3 left over (like a couple of pounds) from my freshwater planted tank days :)
 
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Actually, I prefer Calcium Nitrate over Potassium Nitrate, however something consumes quite a lot of Potassium in my tank so if a test shows it under 380 at the same time as I need to dose Nitrate, that's the bottle I reach for :)

I have a lot of KNO3 left over (like a couple of pounds) from my freshwater planted tank days :)
For a while I used KNO3 from stump remover but as I got more and more coral I also got more nervous about using stump remover. It was much easier for me to find a grade of NaNO3 that I trusted than Ca(NO3)2. So I started using the sodium nitrate. I probably don’t add enough to worry about potassium anyway, but since I didn’t test for it I decided to switch to be safe.
 
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IMO, here's a summary of N dosing preferences, assuming all of them are equally pure and are dosed safely:

calcium nitrate > sodium nitrate >> potassium nitrate

ammonium = amino acids > nitrate

Note the >> between sodium and potassium is intentional as I consider potassium nitrate among the poorest choices unless you are monitoring potassium and know you need it

In most cases, sodium nitrate dosing is perfectly adequate. The only significant concern, IMO, is that in a low alk demand tank, alk can rise higher than is desired.
 

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Actually, I prefer Calcium Nitrate over Potassium Nitrate, however something consumes quite a lot of Potassium in my tank so if a test shows it under 380 at the same time as I need to dose Nitrate, that's the bottle I reach for :)

I have a lot of KNO3 left over (like a couple of pounds) from my freshwater planted tank days :)
I use KNO3 for the same reason lol.
 
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IMO, here's a summary of N dosing preferences, assuming all of them are equally pure and are dosed safely:

calcium nitrate > sodium nitrate >> potassium nitrate

ammonium = amino acids > nitrate

Note the >> between sodium and potassium is intentional as I consider potassium nitrate among the poorest choices unless you are monitoring potassium and know you need it

In most cases, sodium nitrate dosing is perfectly adequate. The only significant concern, IMO, is that in a low alk demand tank, alk can rise higher than is desired.
When it comes to nitrate being used by corals do you think there is a difference between nitrate from the nitrogen cycle, and nitrate that was directly added from one of the 3 compounds?
 
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When it comes to nitrate being used by corals do you think there is a difference between nitrate from the nitrogen cycle, and nitrate that was directly added from one of the 3 compounds?

No. Once it is nitrate, it doesn’t have any memory of where it was born and no subsequent process can distinguish them.
 

Randy Holmes-Farley

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IMO, here's a summary of N dosing preferences, assuming all of them are equally pure and are dosed safely:

calcium nitrate > sodium nitrate >> potassium nitrate

ammonium = amino acids > nitrate

Note the >> between sodium and potassium is intentional as I consider potassium nitrate among the poorest choices unless you are monitoring potassium and know you need it

In most cases, sodium nitrate dosing is perfectly adequate. The only significant concern, IMO, is that in a low alk demand tank, alk can rise higher than is desired.

I would just add this caveat to my preferences above that amino acids may drive processes such as bacterial growth, similar to organic carbon dosing, that are additional effects that a reefer may or may not want to happen in their system, so there are situations where amino dosing may be a poor choice (excessive cyano, for example).
 

Dennis Cartier

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I am curious about something. In another thread you mention that dosing ammonium chloride will lower alkalinity. Why is that and does this same affect apply from the ammonia created by fish respiration?

I would have thought that dosing ammonium would have been neutral and a wash, but it appears to be the ying to nitrate's yang of raising alkalinity.
 
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Randy Holmes-Farley

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I am curious about something. In another thread you mention that dosing ammonium chloride will lower alkalinity. Why is that and does this same affect apply from the ammonia created by fish respiration?

I would have thought that dosing ammonium would have been neutral and a wash, but it appears to be the ying to nitrate's yang of raising alkalinity.

Ammonia dosing (and fish excretion of ammonia) is neutral to alk long term.

Ammonium chloride is essentially ammonia plus HCl (hydrochloric acid). Thought of that way, it is easier to see why it depletes alk:

NH3 + HCl —> NH4+ + Cl- (ammonium chloride)
 

Dennis Cartier

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Ammonia dosing (and fish excretion of ammonia) is neutral to alk long term.

Ammonium chloride is essentially ammonia plus HCl (hydrochloric acid). Thought of that way, it is easier to see why it depletes alk:

NH3 + HCl —> NH4+ + Cl- (ammonium chloride)
Ok, that makes sense.

I will be sure to offset the ammonium chloride with 1.57g of baking soda for each 1g of ammonium chloride to account for the alk requirement. Thanks.
 

Randy Holmes-Farley

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Ok, that makes sense.

I will be sure to offset the ammonium chloride with 1.57g of baking soda for each 1g of ammonium chloride to account for the alk requirement. Thanks.

Sounds like a good plan. :)
 
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Dennis Cartier

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Just to confirm my numbers, using the following post, I calculated 296.09g of Ammonium Chloride dissolved in 1000ml of RO will give me a solution where 1ml dosed into 100G will provide 0.25 ppm of ammonium.


Also while searching around for the answer myself, I noticed that Ammonium Nitrate is 33.5% N, and Ammonium Chloride is 25-26% N. Is the 33% you used in your calc correct for Ammonium Chloride? I am not sure if ammonia content and N content are the same thing ...
 

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Randy Holmes-Farley

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Just to confirm my numbers, using the following post, I calculated 296.09g of Ammonium Chloride dissolved in 1000ml of RO will give me a solution where 1ml dosed into 100G will provide 0.25 ppm of ammonium.


Also while searching around for the answer myself, I noticed that Ammonium Nitrate is 33.5% N, and Ammonium Chloride is 25-26% N. Is the 33% you used in your calc correct for Ammonium Chloride? I am not sure if ammonia content and N content are the same thing ...

Ammonia is NH4 and weighs 18 grams per mole. Chloride weighs 35.45 g/mole. ammonia is 17 g/mole.

ammonium chloride is 17/(18+35.45) = 32% ammonia or 18/(18+35.45) = 33.7% ammonium.
 

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Sorry, one more follow-up question. If I use sodium carbonate instead of bicarbonate, is the offsetting amount 1:1?

When I did the math, converting to carbonate, 1.57g x 0.6313131313 = 0.9911616161g

So 1g:1g then?

Yes.

One sodium carbonate adds twice as much alk as one sodium bicarbonate.

one mole of acid from ammonium chloride weighs 53.5 g/mole.

to offset that acid with alk, you need one NaHCO3 at 84 g/mole, or 84/53.5 = 1.57 x the ammonium chloride. If you offset it with Na2CO3 you need 0.5 x 106 /53.5 = 0.99 x the ammonium chloride used
 

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So I mixed this up last night. I went with 120g to 1L which should give me 0.1 ppm of ammonium per 1ml dosed into 100G.

However I ran into an issue getting it to dissolve completely. I added the ammonium chloride first to the water and mixed it on my stir plate, and then added the sodium carbonate. The carbonate did not mix at all initially, just collected on the bottom in a plug of undissolved powder. I broke up the layer of powder with my magnet retriever and eventually got it to mix, but the solution stayed cloudy. I thought it might be a result of the ammonia, but this morning when I checked the IV bag I am dosing from, there was a 1/4" layer of fine particulate along the bottom seam of the bag. A few quick squeezes and the powder went back into suspension.

Could this be some precipitate from impurities in the sodium carbonate or ammonium chloride? They should have mixed completely right?

The solution will last me several months, but next time I am thinking of mixing the sodium carbonate fully before adding the ammonium chloride in as the ammonium chloride has a higher solubility.

Update: I think I found the cause. The ammonium chloride has an anti-caking agent in it, tricalcium phosphate. This would cause some calcium carbonate to form when the sodium carbonate is added?


Update 2: It looks like tricalcium phosphate has a very low solubility in water (1.2mg/Kg), so I am thinking the powder in the suspension is the tricalcium phosphate that is too insoluble to dissolve.
 
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