# Urea vs KNO3



## SCMurphy (Oct 21, 2003)

Urea breaks down into two ammoniums and a CO2, I suggest it when someone is dosing too much K and starts to see what looks like calcium deficiency on Hygros and the delicate Ludwigias. I've used it for years, never had a problem. Keep an eye on your water parameters while you get used to using it though, you don't want to over do it, too much of any fertilizer can be a bad thing.


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## jgc (Jul 6, 2005)

am I getting confused? kno3 is saltpeter - should be available in a grocery store in small quanities. It is a very common preseravitve used in sausage. Please forgive me if I am getting my chems confused though.

That said, I ordered mine from greg.


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## m.lemay (Jul 28, 2002)

I've heard that Urea is a form of ammonia, am I wrong? 
Have you tried testing for ammonia while using this product?
From everything I've read, Urea is ammonia and it can be deadly to fish and promote algae.

When I used to use the Jobes sticks in my substrate, and kicked up the substrate, it would usually trigger an algae outbreak. I always attributed it to the urea contained in the Jobes.

Marcel


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## Rex Grigg (Dec 10, 2002)

jgc said:


> am I getting confused? kno3 is saltpeter - should be available in a grocery store in small quanities. It is a very common preseravitve used in sausage. Please forgive me if I am getting my chems confused though.
> 
> That said, I ordered mine from greg.



KNO3 = saltpeter. When I was growing up you could get it at any drugstore. Now days it's a lot harder to find. But not impossible in the US. However in some countries it's almost impossible to obtain due to the fact it can be used to make low grade explosives.


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## SCMurphy (Oct 21, 2003)

jgc- medicineman is in Jakarta, Greg might be out of the question.

Marcel- Urea is broken down by plants that have the right enzyme into 2 NH4+ ions and a CO2. It is not a 'form' of ammonia, but it does break down into ammonium over time or more quickly if plants take it up. Think of it this way, your body creates urea to sequester ammonium ions in a form that won't readily turn back into ammonium.

Like I said, I've used it for years, no problems, just don't go crazy with it.


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## jgc (Jul 6, 2005)

Understood, I mentioned greg, not as an option, but to indicate that I have no personaly experiance using saltpeter (other than sausage making that is - I get together with some friends once a year and we make close to 1 ton of sausage - mostly with other preservatives, but some with saltpeter). 

Salt peter is very available in the small rual town I grew up in because it is used in smoking meat (home curing and canning are still a way of life there). It is somewhat overpriced though.


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## g8wayg8r (Dec 24, 2003)

I would never put urea in any tank. Ammonia will eventually lead to a big time algae problem. Nitrates balanced with phosphate, potassium, magnesium and traces will grow plants, not algae. That's the word around here and it seems true in my tank.


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## SCMurphy (Oct 21, 2003)

g8wayg8r said:


> I would never put urea in any tank. Ammonia will eventually lead to a big time algae problem. Nitrates balanced with phosphate, potassium, magnesium and traces will grow plants, not algae. That's the word around here and it seems true in my tank.


No one said you have to. However, the urea is broken down inside the plant to ammoniums and CO2, where coincidentally, nitrates are also broken down into ammonium in a similar process. So, you would be adding ammonium either way.


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## medicineman (Sep 28, 2005)

I see that plants can utilize urea right away by the meas of enzyme digestion.
I will continue using urea because adding NPK does not create a good balance due to using all NPK altogether without any control of how much of which. Well I have no algae problem so far, because I'm using ferts on moderation based on feeling, experience and infos from here and there. In fact I have no test kit at all (well I do have a pH indicator at least). Looking at the quantity, size and physical appearance of the plants I have been dosing and adjusting DIY CO2 level as a balance. After WC and a redo in DIY CO2, more ferts of more variety. On lesser CO2 days and some time after WC, lesser and fewer ferts.


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## kekon (Nov 2, 2006)

What amounts of urea do you dose into your tanks ?


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## spypet (Sep 15, 2006)

why not simply increase the bioload in the tank
(more fish) and/or decrease the amount of plants.
that way you can increase net No3 naturally.


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## TWood (Nov 1, 2005)

KNO3 is also sold as stump remover in the big box lumber stores.


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## kekon (Nov 2, 2006)

Using urea instead of NO3 allows you to have soft water and no calcium defficiency. Nitrogen form has an effect on calcium deficiency. I found an article where an experiment was carried out using NO3 and urea. I had severe calicium deficency when NO3 was high. When i stopped to dose NO3 all the symptomps are going away. I have plenty of KNO3 and urea (two bags of 5kg each) for a very low price. I also began to dose nickel as it is needed by urease enzyme.


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## Hypancistrus (Oct 28, 2004)

g8wayg8r said:


> I would never put urea in any tank. Ammonia will eventually lead to a big time algae problem. Nitrates balanced with phosphate, potassium, magnesium and traces will grow plants, not algae. That's the word around here and it seems true in my tank.


Ammonium (NH4) is much closer to an amine (NH2) which plants use to make plant proteins. It is a better source than nitrate, which plants must convert first.

Urea is a complexed form of ammonium. Algae is too simple a plant to break down the complex, so it will not lead to an algae problem if it is dosed in moderation.

An even better source is guanidine, which is two NH2's and a carbon atom. Seachem's Flourish Nitrogen uses this.


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## plantbrain (Dec 15, 2003)

medicineman said:


> Hi
> It is quite difficult to find KNO3 here (as you know that KNO3 could be used by the wrong hands to set up a terrorizing bomb), so I have been using garden Urea (CON2H4 aka Carbamide) for nitrogen source. Effect is so far as observed, quite good for plant aquaria. Without any shown bad effect to fish and plants as well as no algae shows up after dosing urea, I keep on using it for a very cheap fert. As far as I know, urea needs to be broken down by bacteria to become a form of nitrogen which can be utilized by plants. How about KNO3? What do you think?


You can use it, if you like various forms of algae and like harming fish, it pretty much goes right to NH4 upon addign it to water.
You can avoid algae etc if you do large daily water changes on the days you add it(give it a few hours, then change the water).

Just order some KNO3, does not cost that much and shipping is the main cost issue. Also, try going to the Pharmacy.
Ask for potash of nitrate, saltpeter etc, they typically will sell it there.


Regards, 
Tom Barr


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## plantbrain (Dec 15, 2003)

kekon said:


> Using urea instead of NO3 allows you to have soft water and no calcium defficiency. Nitrogen form has an effect on calcium deficiency. I found an article where an experiment was carried out using NO3 and urea. I had severe calicium deficency when NO3 was high. When i stopped to dose NO3 all the symptomps are going away. I have plenty of KNO3 and urea (two bags of 5kg each) for a very low price. I also began to dose nickel as it is needed by urease enzyme.


Tbhat may just be a symtom of fast growth vs slower growth, the high NO3 lead to faster growth without abalancing the other factors, when you stopped adding it, things settled down again.

This cascade effect is very common in the hobby and leads folks to believe something causes something, when in truth, it's mere correlation is all, it does not imply anything.

They said this about PO4 causing algae as an exmaple.

Regards, 
Tom Barr


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## kekon (Nov 2, 2006)

I was told by a chemist who deals with organic salts that plain guanidine doesn't exist because it's extremely reactive. Seachem contains urea (not guanidine). I have guanidine carbonate and i tried it in my tank but it failed to work. The chemist told me that such salts as guanidine, guanidine carbonate etc. are completely unsuitable for plants because nitrogen atom is bounded with carbon one thus making nitrogen to be very stable and unavailable for plants.
When it comes to NH4 i added 0,5 ppm daily without any algae issues. Also, when i dosed urea (0,5 ppm NH2) daily i didn't have any issues either. But i believe the maintaining such levels in the water column all the time would lead to algae bloom.
I was told over and over again: "your problem is not K vs Ca, your problem is low CO2 and NO3, PO4". So i tried high NO3 - i added Ca(NO3)2 to have more than 20 ppm (i measured water sample in a laboratory) and within 3 days some of my plants looked like dead. I had decent PO4 and CO2 at that time (1 ppm PO4, over 30 ppm CO2). I stopped to dose NO3 and plants responded with healthy growth (of course too low NO3 makes plants to grow slower - we all know it). What i'm saying is that we don't need to have high or very high NO3. It seems 10..15 ppm is quite enough. Besides i don't want my plants to grow as fast as they do in greenhouses. I want them to look healthy, without deformations etc.


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## plantbrain (Dec 15, 2003)

10-15ppm is fine for NO3, the issue is more that folks use test kits that are inaccurate, they assume they are accurate because someone else calibrated the same cheapy brand and thinks they are accurate, rather than doing their's on an individual basis. If you have a lab, then you know to calibrate before running the test each time. 

Few hobbyists do this, very few. 
So they get a reading that says 40ppm and they have really 5 ppm or less.

You suggest to have issues with higher NO3 and plant growth.
I've run plants at 30ppm for several weeks in careful conditions and never saw what you saw nor imply.

I did see however, increased vigor over time.
It appeared that even at high dosing well above 30ppm , that the plants have done exceedingly well.
About 40ppm added per week over 6 weeks.

Note: there where no fish nor sources of NH4 in the tank other than the plant's leaching. Almost all the N was NO3 from KNO3.

In another tank with high fish density, feeding and high NO3 levels consistently for several years, there also has been excellent health, but when the CO2 drops, the result you suggest seem to appear consistently, not only in this case, but in many tanks with a wide range of folks experiencing similar issues. Same was true for the fish health, the health went down with lower CO2.

Cascade effects are typical, adding more of one nutrient increases demand for the others, 3 days is not enough time to accurately gauge adaption to a new routine. It might be trace elemtns Mg, etc, I'm not sure what your plants did, etc.

My point is relatively simple: I add much more than 20ppm of NO3, as do many folks, and we do not see the same response, to be what you suggest as cause, not a correlation, we should also see the similar effects.

The same approach is used with algae and PO4, if we accept that the hypothese says excess PO4 = algae, and we add excess PO4 repeatedly, and get no algae blooms, then we can safely assuem that PO4= algae is not a valid hypothese in and of itself. We will reject that hypothese and form a new one.

Likewise, low Ca and high K+ levels have been tested, this is an easy test to do. I nor others where able to show that high levels of K+ inhibited in any manner Ca++ uptake in _Ammannia_, a supposedly suspectible plant to high K+ levels.

Knowing what something is not with certainly is useful information.
That gets you much closer to figuring out what it might be the cause and along the way, you learn more and have more flexibilty with the past test, for your future routines.

I've gotten burned by CO2 more than I can count. 

I can rule out NO3 and PO4 and Ca and K+ etc easily.
CO2 is relatively easy as well but unlike NO3, PO4 etc, the levels change on a _much faster time scale _and can vary to a much larger degree.so you need to pay close attention for several days and make sure things are goign well throughout the day period(night does not matter)

I've used NH4 for several grow out projects for aquatic weeds as well as substrate based NH4 and urea based sources.

But generally these are followed with lots of water changes, I've left things go or added too much and the gain is simply not worth the risk for most cases. If you add only a tiny bit and do not go wild with it, then you'll do fine with urea and NH4, especially if you have low light tanks, for higher light tanks, the risk is higher........

But as said and suggested, add more fish if you think you need more NH4 and top off with KNO3.........

Fish dose the NH4 very well via waste.
a balance of NO3 from KNO3 and NH4 from fish would seem to produce the best growth.

Oddly, I found for many species that the KNO3 as a sole source did better in terms fo growth rate and lower incidence of algae, the algae part I can explain, less NH4 etc, the higher growth I'm still scratching my head about.



Regards, 
Tom Barr


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## kekon (Nov 2, 2006)

I suspect that Ca(NO3)2 which was my NO3 source was harmful to some plants. I noticed green plants (Blyxa japonica, H.callitrihoides, cardamine lyrata, Cabomba caroliniana) did very well under Ca(NO3)2 fertlization. They grew like crazy. Other plants however, especially red stem plants (A.reineckii, Rotala indica, didilis) suffered from Ca(NO3)2 dosing very much. A.reinecki was totally stunted and deformed and didn't grow at all. Even Polysperma Rosanervig which is considered to be a simple plant to grow grew very slowly and sometimes showed Ca deficiency. Adding more Ca up to 50 ppm helped but not much. At that time i had the following parameters (all measured in certified lab):

Tank 200 liters
Ca: 45 ppm
Mg: 8 ppm
NO3: 16 ppm 
PO4: 1 ppm
K: 11 ppm 
SO4: 30 ppm
Cl: 2..5 ppm
Na: 2..12 ppm
lighting: 150 Watts 

Adding more micros (such as boron, zinc, molybdenum) made things even worse. Adding more boron (added 0,03 ppm from H3BO3) caused stunted growth and chlorosis on new leaves. Adding zinc didn't cause chlorosis but stopped the growth immediately. I suspected molybdenum deficiency at the beginning but adding some of it didn't change anything.
The strange thing is that after lowering NO3 i noticed much higher demand for iron (chlorosis appeared on many plants on their new leaves).
I also made my own micro fert but it had very little Cu (much less than TMG has; TMG - 0.006%; my fert: 0,002%) and i got Cu deficiency which looked exactly as in the photo:

Plant Physiology Online: Visual Symptoms of Nutrient Deficiency In Plants
(figure 5.1.K)


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## kekon (Nov 2, 2006)

Hmmmm, it seems i was misinformed...


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## plantbrain (Dec 15, 2003)

kekon said:


> I suspect that Ca(NO3)2 which was my NO3 source was harmful to some plants. I noticed green plants (Blyxa japonica, H.callitrihoides, cardamine lyrata, Cabomba caroliniana) did very well under Ca(NO3)2 fertlization. They grew like crazy.


This is very expected actually, these are hungry faster growing weeds, I have seen the same thing using KNO3 in growth responses. 



> Other plants however, especially red stem plants (A.reineckii, Rotala indica, didilis) suffered from Ca(NO3)2 dosing very much. A.reinecki was totally stunted and deformed and didn't grow at all. Even Polysperma Rosanervig which is considered to be a simple plant to grow grew very slowly and sometimes showed Ca deficiency. Adding more Ca up to 50 ppm helped but not much. At that time i had the following parameters (all measured in certified lab):
> 
> Tank 200 liters
> Ca: 45 ppm
> ...


The lowering of NO3 and so called Fe deficicency was really NO3 deficicency.
Many think it's Fe but it's lack of NO3.

Note, the crops often used to cite aquatic macrophyte deficiencies are very crop specific. Many also over lap and look similar.

I'd sugest you do frequent water changes(50-% weekly) and then dose 3x a week or so.

R indica, D diandra, and Hygro all grow very fast at higher NO3 levels.
Water softness, the Kh specifically seems to affect them a little, but that should not be that large of an issue.

I'd do this:

50-70% water change per week
Add 3x a week:

1/2 teaspoon KNO3
1/8 teaspoon KH2PO4
Tropica Master Grow 10mls

CO2.......this needs to cranked up enough to see pearling after 1-3 hours.
CO2 is the Achillies Heel here, you can test the nutrients and chase them all over, but if you do not have the same adherence to rigor with CO2, they will forever be confounding factors in any analysis you might do.

You cannot get away from that.

You can measure CO2 accurately and throughout the day via a KH reference vs the tank's KH and then use a pH meter. 

Regards, 
Tom Barr


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## plantbrain (Dec 15, 2003)

http://www.seachem.com/support/MSDS.pdf

If it's dilute, then it's obviously not very concentrated and designed for the conservative side, all aquarium ferts are designed in this manner.

I spoke with Claus, maybe 7-8 years ago about this and complained folks never added more than the suggested fert amounts on labels and that was why folks had many issues, he did not bat an eye, he said "Yes!". He also told folks in the local club to add 2-3x the suggested amounts as their plants where very deficient.

I question the efficiacy of guanidine for plants vs say Urea/NH4 and NO3.

Clearly NO3 is the best of the 3, but you cannot get away from some urea and NH4 via fish waste.

I've not seem dramatic difference in growth due solely to the additive effects of NH4 nor urea vs NO3.

I've done the test a few times, still I ain't seeing it, but I will hold out for plant specific preferences, but after perhaps 40 species run on such test, I'm still coming up with nothing.

Oddly, and not what I would ahve predicted, the NO3 dosign actually did better than the NH4.

I have a few theories as to why that might me also.
Both test had 2 weeks of acclimation to the form of N.
While both NO3 uptake and NH4 have some consititutive expression for HATS(high affinity transport systems) and control(eg, NO3 uptake will be supressed when the NH4 levels are say 0.5ppm or higher) the NO3 has multiple LATS(low affinity transport systems) that have been characterized. 
With steady high rates, of NO3, the plants may adapt to such conditions and once adaptation/acclimation occurs, then trhe plants may grow at a very high rate once the enzymatic machinery is stable and in place.

Bouncing the levels all over is bad for the plant.
If the levels are high and vary say between, 20-30ppm NO3 vs 0-10ppm, which is better?

The same is true for CO2.
Plants adapt to low CO2 and also high CO2.
What they do not like is switching back and forth between such levels.

I'd say the same is true for Urea also, a good steady rate will be helpful for the filter bacteria as well as the plant uptake.

Regards, 
Tom Barr


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## kekon (Nov 2, 2006)

plantbrain said:


> The lowering of NO3 and so called Fe deficicency was really NO3 deficicency.
> Many think it's Fe but it's lack of NO3.


It wasn't NO3 deficiency because i added more Fe and symptoms are dissapearing. N deficiency always showed in my tank as yellowing older leaves while maintaining upper leaves in normal color.


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## plantbrain (Dec 15, 2003)

Sounds like the low NO3 is ruled out then and appears to be a safe assumption, good.

Is your water hard? high KH?

Often that makes a fairly significant difference.
TMG seems to work very well for this.

I think many folks try and limit Fe for some odd reason, likely due to past issues with algae claims and that algae likes high Fe etc.

I've never once in any test found a link between algae blooms, increased growth and Fe/trace dosing. That's been about 15 years worth and perhaps 100 tanks or more.

Even your best test methods will have trouble applying a residual to bioavailable Fe in a tank. But you can add more and watch the plants, they do make a decent indicator, but you have to rule out the other nutriente carefully, most do not do this.

The other issue with nutrients, when folks prune a lot, they often keep adding the same amount of ferts, also, after a peroid of sayb 3-5 weeks of intense growth, they still add the same amount even though the plant biomass have increased by 5x or more.

Responding to biomass increases and decreases can make folks assume incorrect notions about uptake and demand and deficiencies.

Most folks have fallen into this issue as well at least a few times.

A tank with 5x the active growing biomass will have a much better experience with Urea and NH4 than someone with much less.

But it's a trade off about how much dosing and ferts folks want to add, maintaining stable biomass will help to maintain and stable uptake and dosing level.

Regards, 
Tom Barr


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## kekon (Nov 2, 2006)

KH is 3..4, Ca = 25, Mg = 8.
When it comes to algae bloom caused (as many think) by Fe it seems to me it's a matter of kind of chelator rather than Fe itself. I had fert based on DTPA chelator and i didn't have algae issues. Then i tried EDTA chelator (used normally for hydroponics purposes) and it turned out to be worse and caused thread-algae to grow. Maybe because it was due to lot of NH4 which is built into EDTA structure. As far as i know TMG contains HEEDTA and DTPA and my tank was free of algae when using it.


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## plantbrain (Dec 15, 2003)

I have not noted any chelator differences in algae, but rather, it overall plant health.

I do prefer TMG over any EDTA version.
But such differences tend to be rather minor in nature but enough to warrant the use of TMG.

Regards, 
Tom Barr


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## medicineman (Sep 28, 2005)

Wow.. the thread is quite some time old ever since I first throwed the question. Now I have lots of KNO3, obtained from chemical dealer by using our company background as a legal permit (we deal fert, pharmacy, etc). I can even get a hundred or two lbs now. Not just a simple fert, cummulated experience and research even resulting in my own version of TMG and how I'm glad for that. No more urea for me now, too risky when I happen to accidentaly overdose.


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