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Toby's Urea Fertilizer?

G H Nelson

G H Nelson

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This recipe Spezial N - Nitrogen Fertilizer advised to be used at pH below 7.
Considering most tap-water is above that pH.....before injecting Co2 is there any real benefits?
What would the consequences be if dosed regularly at pH 7.5 say with fish/shrimp in the aquarium?
 
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Hi all,
GHNelson said:
This recipe Spezial N - Nitrogen Fertilizer advised to be used at pH below 7.
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I assume that is to cover them, just because of the <"toxicity of ammonia (NH3)"> when it forms a larger proportion of the TAN.

1809-4430-eagri-36-2-0377-gf01.jpg
GHNelson said:
What would the consequences be if dosed regularly at pH 7.5 say with fish/shrimp in the aquarium?
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I'm hoping that @Zeus.'s urea experiment is going to tell us.

I've tended to equate the toxicity of urea with that of ammonia, but that will over-estimate the dangers to some degree.

cheers Darrel
 
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Hi Hoggie,
Yeah, sure, there is always a benefit in dosing Urea as plants can more easily and efficiently uptake the NH4 than they can NO3. I believe Toby's recipe uses both and that's wise. So you should see better growth and performance than using NO3 alone, however, yes there is that elephant in the room and if care is not taken that elephant will stomp your head straight into the ground.

Cheers,
 
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dw1305 said:
@jaypeecee, I think @Zeus. has been dosing about 1/2 EI levels of nitrogen (N) as urea via a dosing pump? So as a continual trickle rather than as a series of "lumps".
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Hi Darrel (@dw1305)

Thanks for the reply. Any chance of a few more details of your setup, @Zeus. ? Tank volume, livestock, water pH, plants, lighting, etc.? For how long have you been using urea? I assume you've made it up as a solution. If so, what is the concentration of urea in the dosing container and how much is dosed and how often?

I have to admit that urea didn't work for me this time but I'll almost certainly try again. I was dosing at the same sort of level that @JamesC tried many years ago. More details will follow - I promise!

JPC
 
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@jaypeecee sorry read this then got distracted 😳

50l tank CO2 injected dosing an AIO clone of TSN made with Urea Prills instead of KNO3 (so no KNO3), DC yellow, hard water, dont measure pH anymore just accept it, 6 months plus, gets dosed every 12.5 minutes about a drop of clone each dose not same concentration as TSN, high light 6hours, not 100% on the ppm's* ATM which is 😳 but plants are fine no better or worse than when I was dosing EI levels using KNO3, RCS and snails only

500l I slowly increased the amount of UREA in the EI fert mix and was dosing every 2 hrs Macro -Micros of the weekly dose (plants are fine no better or worse- although still had H. Pin issue which I think is tap water related issue ) Hard water, DC light green, light medium to high as have Kessil 160, 5hrs. Low fish load RCS, Amanos, snails. Have been deceasing CO2 levels ready for move, currently no CO2 and dosing an AIO TSN clone with Fe shared between APFUK and Fe EDDHA and 100% urea and using an AIO on both tanks.

Not 100% happy with tanks and think issues are related to fluctuating mineral/metal levels in tap water as some vary 100% over the seasons. Moving very soon( I hope waiting to exchange ATM) and planning moving to RO water so I can control/know whats in the water.

*Sometimes I lose where I'm up to with what ppms I am dosing, with working on the IFC calculator as we ( me and Hanuman) have about 200versions of it and which version I used to make the last batch is on one of them 😬

Do plan to keep better records when I move and move to RO, which will hopefully provide some insight into Urea, also planning to do tanks without AS (Aquasoil) and use sand and inert rocks.

So in short dabbling with Urea ATM but no issues so far, I do 'think' the frequent dosing helps
 
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Zeus. said:
@jaypeecee sorry read this then got distracted
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Hi @Zeus.

No worries.
Zeus. said:
So in short dabbling with Urea ATM but no issues so far, I do 'think' the frequent dosing helps
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I look forward to seeing how things pan out for you. Urea is really interesting stuff. When I try it next time, I'll reduce the dosage even lower. And, I'll try using a dosing pump - that will be a new toy for me! Never used one before so I'll be asking for recommendations.

JPC
 
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ceg4048 said:
Yeah, sure, there is always a benefit in dosing Urea as plants can more easily and efficiently uptake the NH4 than they can NO3.
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Hi @ceg4048

My understanding is that aquarium plants hydrolyse urea using the enzyme, urease. This reaction not only produces ammonia/ammonium but also carbon dioxide. That is a double-win. Or, am I overlooking something?

JPC
 
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jaypeecee said:
Hi @dw1305

That would not appear to be the case:

echa.europa.eu

Registration Dossier - ECHA

echa.europa.eu echa.europa.eu

Note that the above deals with acute toxicity, not chronic toxicity.

JPC
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The [urea] was off the scale compared to what we are dosing in reference to livestock toxicity.

Remember reading about fishing on the River Trent many moons ago, some of the best fishing was downstream of a water treatment plant which was pumping lots of untreated waste into the river, which resulted in massive increase in food for fish and lots more fish to catch, I believe the best spots was close to the output, however the river did have a nasty smell on the best spots
 
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jaypeecee said:
My understanding is that aquarium plants hydrolyse urea using the enzyme, urease. This reaction not only produces ammonia/ammonium but also carbon dioxide. That is a double-win. Or, am I overlooking something?
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Perhaps you're overlooking the fact that the NH4 can be turned into NH3 if the pH rises above neutral where fauna are susceptible to toxicity. The article you reference involves a species adapted to withstand high levels of the toxin whereas we cannot automatically conclude that the same can be said for Discus, for example.

Carbamide itself is not very toxic, as your article suggests, however, it does not discuss the results of the effects of urease on that concentration of urea, so again, the data can be misinterpreted. Was the LC50 and LC96 toxicity a result of the carbamide or was it caused when the carbamide degraded into NH3? What agent actually killed the fish? Was it a bare tank or was there mature sediment rich in urease? Do you imagine that after dosing, the urea immediately enters the plants or did you consider that the urease in the sediment will have first opportunity to hydrolyse and therefore dump NH3/NH4 into the water column?

As I mentioned, if you know what you're doing then urea can be used responsibly but for people who don't know what they are doing they can suffer fish illness/death and can trigger algal blooms.

Cheers,
 
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Hi all,
jaypeecee said:
I quoted this one source of toxicity data but there are others.
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I've been thinking about this, and I think Clive is right, the potential source of uncertainty is the rate at which urea is catalysed to ammonia <"by urease">, and both that rate, and the fate of the ammonia hydrolysed, are going to have lots of potential variables, like:
  • Nature of the microbial assemblage,
  • nature of the floral assemblage,
  • dissolved oxygen availability.
  • pH
  • Temperature
I haven't had an exhaustive look but these look quite interesting.
Liang et al (2003) "Roles of substrate microorganisms and urease activities in wastewater purification in a constructed wetland system" Ecological Engineering 21, pp 191-195 says:
........Meanwhile, there was significant positive correlation (P<0.05) between urease activities and removal efficiencies of TKN and negative correlation between urease activities and removal efficiencies of BOD5. Substrate microorganisms and urease activities played key factors during purification processes and they could be utilized as indicator of wastewater treatment performances in the constructed wetland system .......
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Kumar et al (2020) "Variation in extracellular enzyme activities and their influence on the performance of surface-flow constructed wetland microcosm (CMW)" Chemosphere, 251 pp says:
...... Activity of urease and NH4+-N removal was positively correlated with significant positive correlation in CWM units planted with Phragmites karka, and Pistia stratiotes (Ph + Pi) and Typha latifolia, Phragmites karka and Pistia stratiotes (T + Ph + Pi). Urease activity was found to be both positively and negatively correlated with respect to removal of NO3−N and NO2−N in different CWM units..........
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Thorén , Legrand & Herrmann (2003) "Transport and transformation of de-icing urea from airport runways in a constructed wetland system" Water Sci. Technol. 48:5 pp. 283–290 says:
.......This indicated that 75% of the urea was transformed before entering the wetland. Urea was found to be only a minor part (8%) of total-N in the wetland influent. Calculations of cumulative urea-N loads at the wetland inlet and outlet respectively, showed a significant urea transformation during February 2001 with approximately 40% of the incoming urea-N being transformed in the wetland system. These results show that significant amounts of urea can be transformed in a wetland system at air temperatures around 0°C. ........
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cheers Darrel
 
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