Dosing with Ammonia and Urea

[JamesC]

Decided to open a new thread on this very interesting subject rather than carry it on in the Good Algae Article thread - http://ukaps.org/forum/viewtopic.php?t=905

Here's what been said so far:

As George alluded to, some vendors use ammonia salts as their source of N, which I find completely astonishing. Probably the levels are low enough if dosed properly, but I don't see the point. I might be missing something so I want to study this some more.

Let us know how you get on mate. I read somewhere that plants have an 'easier' time using it for their N source than KNO3. I'm no biochemistbotanist though...

But I know I don't get algae. 😉

I looked at ammonia additions to tanks a while ago. A few notes for you.

Seachem Nitrogen uses guanidine and potassium nitrate as their source for N. Guanidine is similar to urea. I think I'm correct in believing that plants can utilise the Urea but algae can't - may need to check on this.

Tropica use ammonium nitrate but I think it is bound up somehow so it's not like adding ammonium salt - need to confirm this.

Some people have been exprerimenting using urea with good results, but others haven't.

A thread just started on APC might be of interest - http://www.aquaticplantcentral.com/...aquarium-plants-preference-ammonium-over.html. Follow Freemann's link to the Barr Report as well.

Hey James, thanks for that bit of clarification. I remember trying Scott's terrestrial fertilizer which contained urea and ammonium nitrate. It worked well as long as I had a huge biomass, dosed small amounts and kept up the water changes, but it was living on the razors edge and any other mistakes I made seemed to be exacerbated by using the product. I was under the impression that urea broke down into other components including ammonia, but if urea is not available to algae then that might explain things. I'm very interested in understanding the mechanism of how TPN+ binds the ammonium nitrate. Can't argue with Georges success using it. 8)
Cheers,

I'm going to look into this a bit more and I might even test with dosing some urea to see how it goes. To what I can gather it works best in a fully planted tank with CO2 and plenty of all the other nutrients.

Urea needs an enzyme called Urease to be broken down.

Dosing is still fairly critical because urease is naturally occuring so the Urea will be broken down in the tank creating ammonia.

To what I can gather dosing Urea may benefit soft water tanks more than hard water tanks. In the link I posted above there is talk to why this may be so.

James

 

[ceg4048]

Excellent! Thanks for that James. I've been studying the APC thread and what baffles me the most is the post #9 in that thread where the poster reports stunting/dying and yellowing of the plants when dosing KNO3. I've seen just the opposite - and that's been in RO water at times and tap at other times. I can revisit this though. James any idea where to source the urea granules?

Cheers,

 

[JamesC]

There's been some debate about high NO3 levels in water with a very low GH. Some people have no problems while others have no end of problems. The main problem plant seems to be Alternanthera Reineckii which some have said suffers with NO3>10ppm and GH<4. Tom Barr has just finished an experiment that shows that this is not the case. But Tom used ADA AS which the other people didn't so that might explain something. I know I have always had problems with Alternanthera reineckii in my silica sand substrate under both EI and the PMDD+PO4 dosing I do now. Strangely it's only Alternanthera reineckii that struggles, everything else grows really well.

This is one of the reasons I looked into urea dosing as I'm not convinced it's anything to do with NO3 levels. I've actually just brought some more Alternanthera reineckii to see if I can grow it now. Luckily my wife works in the labs at a college so I can get hold of most chemicals. Got some Urea coming home tonight 😀 . Won't start using it for a while though as I'm away next week. I'll update when or if I start dosing. Need to go and spend some time to see what levels others are dosing first, but am well busy at the mo so will have to wait.

Oh, I can grow Alternanthera reineckii really well actually by just lowering my lighting right back and slowing everything down, but I like to have a challenge and work out the reason's why things happen.

James

 

[George Farmer]

You crazy scientists - I love it though!

 

[ceg4048]

...I know I have always had problems with Alternanthera reineckii in my silica sand substrate under both EI and the PMDD+PO4 dosing I do now. Strangely it's only Alternanthera reineckii that struggles, everything else grows really well.


...Oh, I can grow Alternanthera reineckii really well actually by just lowering my lighting right back and slowing everything down, but I like to have a challenge and work out the reason's why things happen....

James

Hi James,
I'm having a twilight zone experience again. I mean, A. reineckii has always been a weed for me whether in RO, tap or RO+tap. The plants I have now I got from Pets-are-home where, following beeky's advice, I got them to give me the surface scrapings from their plant holding tank for free. I chucked the slivers in the tank and never looked back. It grew like gangbusters and I even sent some to daniel1983 who chucked it in his tank and never looked back (from all accounts) http://www.ukaps.org/forum/viewtopic.ph ... c&start=50

After reviewing that Barr thread I saw where the original poster was having difficulty with distorted leaves and was blaming NO3 for it, which I thought was unbelievable. NO3 is being blamed for stunted growth, yellowing of leaves and malformed plants all in the same lifetime. I may be one of NO3's last defenders!😛

I'm going to fire one shot in response. Now, there is some yellowing on the L. aromatica. I think that's normal coloration but I want to keep an open mind. Maybe urea will give me a darker green? The other thing is the A. reinekii leaves are not flat, but are a bit crinkled. Could that be the problem? I always thought it was normal.


Cheers,

 

[George Farmer]

Now, there is some yellowing on the L. aromatica. I think that's normal coloration but I want to keep an open mind. Maybe urea will give me a darker green?

That's 'normal' IME. Then they go red as they get nearer the light.

But what is 'normal'?! 😛

Super thread guys. Keep up the good work.

 

[JamesC]

I've decided to give dosing urea a go and see if there are any differences. Looking at what other people have experimented with on other forums I have decided to go with 0.5 ppm of urea per day. I have reduced my daily NO3 dose so that the total amount of Nitrogen added remains the same.

The other change I've made is that I normally add the macro's before I go to work in the morning but now will add them when I get home from work when the plants are in full photosynthesis. The thinking behind this is is that if I add the urea in the morning the biological filter will remove the urea before the plants have a chance to use it. But adding it after the lights have been on for a couple of hours will make the urea instantly available. That's the theory anyway.

Today, Saturday is the first day of dosing so I'll keep updating this thread with my observations.

James

 

[plantbrain]

Be prepared to get burnt by dosing NH4.

We went through this in the late 1990's and I suppose all cohorts of aquarist tend to as they go through the hobby.

There are other factors here.
It's not as simple as you are making it out to be.

Fish loads add plenty of NH4, provided you actually keep fish🙂
I have either packed tanks or hardly a thing in there.

Now you can do a few things to see how NH4 influences tanks, plant growth etc, it's not just this one piece meal thing that applies to every tank under all conditions.

There are obvious factors that influence results:

Light intensity- huge differences in algal responses
CO2, turn it off and see.
Filters, take this off to see how much NH4 is being oxidized by bacteria(hint: a lot), wait 4-8 weeks and then see......
Current, reduce this and see.

Plant biomass/filter cleanings water changes etc.

If you do daily 50% water changes, you can dose .6-.8 ppm of NH4 via NH4Cl without an algae bloom, but again, daily water changes.....

Filters are cycled using ammonia, what do you think a filter will do if you add more fish to the tank slowly?

Now what about NH4 added slowly?

You need a method to distingush what is occurring with the plants, not the filter and other factors.

My point is simple, why is adding more fish any different then than adding NH4 and urea?

Is it?

I do not think it really is............and we all like more fish.

I have ADA AS, but the results with the NO3 dosing are no different.
I have the same growth patterns.

NO3 is a lot safer as far as toxicity than NH4 also.
Personally, I'd rather have more fish and feed them better if I want more NH4 in there.

And you really cannot underestimate that filter.
It's a really obvious thing.
At least to me.

So, if you think it's all plant, try removing the filter for a time, 4-8 weeks is often enough, add more light etdc.

Dose away🙂
Question is, "do you feel lucky"?

BTW, if you do this, be prepared.

If you assume that adding NH4 will work well, then you use nothing but fish as the source for N.

Can you over load the tank using fish over stocking and induce algae?
Yep.

In a non CO2 tank, the demand is low, so fish waste alone meets the demands.

As we increase and amplify growth(hardly natural), we need to switch to less toxic forms that we can add with less trouble and error.



Regards,
Tom Barr


Regards,
Tom Barr

 

[ceg4048]

Hallelujah, sanity restored...

Thanks Mr. Barr, but can you comment or explain why the TPN and ADA fertilizers should choose to use NH4 and how it would be bound to avoid algae?

Cheers,

 

[JamesC]

Well I've now been dosing 0.5ppm of Urea daily now for nearly two weeks. Still early days but one thing I've noticed is that the new growth of my Rotala Macrandra is looking really good, more pink and fuller than before. The Alternanthera Reineckii ''roseafolia'' also looks as though new growth is healthier. As it's not such a fast grower I'll need to give it more time.

Most importantly fish and shrimp are behaving as normal and there are no signs of algae. Water is still crystal clear as well.

I'll update again in a few weeks.

James

 

[GreenNeedle]

Just a note.

From my time at William Sinclair (J Arthur Bowers/Silvaperl etc) all composts have Urea as the N in them so quite a few of our members may have already stumbled upon some problems / benefits that apply to this situation.

Andy

 

[ceg4048]

OK, been sniffing around at some of the agricultural sites to see what the advantages of urea are. Urea is available, by the way, at Garden Direct. 1/2 Kilo for £3.25 plus shipping - http://www.gardendirect.co.uk/urea-p-224

The nitrogen content is almost 50% so I can see why this product is surpassing even ammonium nitrate as a crop fertilizer. This compares to KNO3 which is only about 14% nitrogen.

What I'm still a bit confused about though is I couldn't find any description of what happens when it dissolves in water. The agricultural sites discuss the breakdown of the compound in soil, and that the hydrolysis requires the presence of a soil enzyme called Urease:

CO(NH2)2 + H2O + urease -> 2NH3 +CO2

It's not clear to me whether an aquatic plant absorbs the compound in it's entirety and then breaks down the urea internally or whether the breakdown into CO2 and NH3 can occur directly in the water without the presence of this urease enzyme, or whether the compound breaks down according to some other formula. Can you shed any light James?

The next question therefore is: can you achieve the same growth improvement by simply tripling the KNO3 dosage? That would be the next test I would think.

It's also not clear, as plantbrain noted what percentage of the urea product breakdown (if indeed NH3 is released into the water column) is taken up by the bacteria and converted to NO3. Can you measure this accurately?

Cheers,

 

[JamesC]

Some very good questions. Plants don't, I believe, take up urea directly but take up N in the inorganic form. Urea once in the tank will fairly quickly convert to ammonia by either urease or micro organisms in the substrate. It could be possible that bacteria in the filter will do the same but I'm not sure of this. I would guess that urea would convert to ammonia over a period of time which is better than a single large dose of ammonia. As Tom suggested adding more fish to the tank would most likely do the same thing.

To what I can gather from other posts on forums some plants may do better with NH4/NH3 and NO3 rather than just NO3. This is just speculation though. But as some of the major brands add ammonium compounds to their products made me think about it and give it a try. If it has a positive benefit on some of my plants then great, but if it ends in total disaster then I know not to do it again.

I would love to know why Seachem, Tropica, etc use ammonia compounds in their nitrogen products if everyone says it's so bad. There must be more to it than I know. They say it's because plants prefer ammonium compounds to nitrate, which is probably true, but then if plants can use nitrate just as well then why take the risk of adding ammonia?

James

 

[ceg4048]

I would love to know why Seachem, Tropica, etc use ammonia compounds in their nitrogen products if everyone says it's so bad. There must be more to it than I know. They say it's because plants prefer ammonium compounds to nitrate, which is probably true, but then if plants can use nitrate just as well then why take the risk of adding ammonia?

James

James I've been thinking about this question because it baffles me as well. The only conclusion I could draw is cost. If you look at the Garden Direct pricing 1/2 kilo of urea is £3.25 whereas a 1/2 kilo of KNO3 is £5.25. Further, look at the higher N yield - 46% N versus 13% N, almost 4 times as much for urea. Almost certainly, whatever ammonia products are being used in the commercial N products have a less expensive production cost.

Meanwhile, back a the ranch I decided to goad you into committing an error by showing what urea will have to beat. If it can grow A reineckii "roseafolia" better than this I'll be convinced:



Cheers,

 

[Ray]

Very nice experiment James - thanks for sharing your results.

The next question therefore is: can you achieve the same growth improvement by simply tripling the KNO3 dosage? That would be the next test I would think.

I think that is the million dollar question - are you prepared to give it a try James after the urea trial period is over?

The only conclusion I could draw is cost.

I think you've hit the nail on the head there Clive - its certainly the beancounters who have the most influence on what goes in these products not the anti algae guru's... But James isn't reporting any algae triggered by the urea dosing. I'm wondering, as the urea breaks down, does it still pass through a form that can trigger algae - on paper it does but we're not seeing what we would expect :?:

 

[JamesC]

I'm trying Clive. Don't ever think I'll get it as good as yours though as that's one of the nicest specimens I've ever seen.

Even taking the cost difference into consideration I can't believe manufacturers would put ammnoium compounds in their products if it is supposed to be so bad. The amount added to each bottle is pretty small and also they don't actually use urea but guanidine which is similar and also ammonium nitrate I think.

I have 4wpg of HOT5 above my tank and add urea daily and so far there is no signs of any algae.


I've been doing some more searching on urea and it seems that plants that contain the enzyme urease can utilise the N in urea directly. This does depend on how long the urea stays as urea in the water once added. If it converts to ammonia within minutes then it may not make any difference. I wonder if it's most plants that can utilise urea or just a handful.

James

 

[George Farmer]

Fascinating guys.

Love the pics, Clive. Super plant health, bordering on looking artificial!

Is that the rock I gave you at the Festival?

 

[ceg4048]

Hi George,
Hey, I can rough them up a bit if that will help make them look less artificial... 😛

Yes that's one of the rocks "appropriated" from the festival! Remember you gave me two? The second is being swallowed the smaller A. reineckii on the right. I'll have to pull that plant out and replace it with something cleaner, like maybe Blyxa or maybe one of those new super-secret Tropica mutants...:idea:


Cheers,

 

[Ray]

I've been doing some more searching on urea and it seems that plants that contain the enzyme urease can utilise the N in urea directly. This does depend on how long the urea stays as urea in the water once added. If it converts to ammonia within minutes then it may not make any difference. I wonder if it's most plants that can utilise urea or just a handful.

And:

I have 4wpg of HOT5 above my tank and add urea daily and so far there is no signs of any algae.

(as Cliver already said) urease works like this:

(NH2)2CO + H2O ? CO2 + 2NH3

That's quite a nice win for a plant that has urease, a byproduct is CO2 which it also needs - its like a power pill! Is it possible, as I think James is hinting, that the plant takes on all of the urease and uses the CO2 and metabolises the NH3 all in one go? If so then there would be no time for any background ammonia to trigger algae. Assuming urea can't trigger algae this could explain why it is safer than dosing ammonia.

Of course this would be no safer than dosing NH4 directly - I'm willing to bet James' good results are due to increased availability of N rather than anything else and could be duplicated by increased doing of macros :?:

 

[JamesC]

Assuming urea can't trigger algae this could explain why it is safer than dosing ammonia.

To what I can gather algae are not able to utilise urea directly as they lack the urease enzyme.

I'm willing to bet James' good results are due to increased availability of N rather than anything else and could be duplicated by increased doing of macros :?:

And you may be correct, but I had high NO3 before from increased EI dosing and CO2 mist blown directly at the plant and this made no difference. This is what has led me down this path of dosing urea. I shall though if this trial is a success remove the urea from my dosing and replace it with the equivalent amount of NO3 to keep total N the same.

James