Urea and ammonium dosing

[p1u5h13r4m24]

Good morning!
Reefbuilders recently created an article talking about the benefits to dosing urea and ammonia. I started doing this now for about 4 days and honestly my corals are looking extremely happy. I am just wondering if anyone has been doing this and what their experience has been. Can’t wait to hear from @Randy Holmes-Farley on this as I know he supports ammonia dosing.

 

[Randy Holmes-Farley]

There's another thread here:

Urea-n’t Gonna Believe This!

Hey, I just wanted to get people talking about this as it's peaked my interest, I've seen people such as Randy Holmes-Farley talk about the importance of ammonia in our reef aquariums and just read this article on Reefbuilders which goes a step further into that theory with dosing urea and I...

www.reef2reef.com

My thoughts copied from that thread:

I’ve not seen many folks dose urea. Measuring it isn’t possible, so you have to dose blind in a certain sense.

It seems like it would be a fine source of N, but it may not be as useful as ammonia, because to use it, corals have to first convert it to ammonia.

 

[p1u5h13r4m24]

Thanks Randy. When it comes to monitoring urea they suggest the n-doc test. Would this be a reliable way to test? This is what they say about it.
“While overdosing urea is unlikely if you do so conservatively (since it is so widely metabolized), it wouldn’t hurt to periodically check your organic nitrogen levels. As of now, the only way on the market to do this is with a Triton N-DOC test,“

 

[Randy Holmes-Farley]

Thanks Randy. When it comes to monitoring urea they suggest the n-doc test. Would this be a reliable way to test? This is what they say about it.
“While overdosing urea is unlikely if you do so conservatively (since it is so widely metabolized), it wouldn’t hurt to periodically check your organic nitrogen levels. As of now, the only way on the market to do this is with a Triton N-DOC test,“

urea is quite nontoxic so a problem from normal dosing of too much is unlikely.

I would not use a test that detects every form of organic nitrogen as a way to judge urea, however. I'm not really seeing a use of that test for any purpose. It seems to me like a test looking for a reason to use it. I might be convinced that it has uses, but I do not see them at the moment.

 

[p1u5h13r4m24]

Thank you. I’m 4 days in on dosing small amounts. I’ll post my conclusion in a few weeks. I plan on submitting an ICP to be sure the urea I’m using doesn’t contain any other trace issues.

 

[Red_Beard]

How is your testing going?

 

[Randy Holmes-Farley]

It would be interesting to see a comparison of different N sources. I’m not seeing any reason to think urea is better than ammonia since organisms will have to convert it to ammonia before most uses, but there may be issues we are not aware of. :)

 

[Red_Beard]

Agreed, a comparison would be very interesting to see.
Most of the limited number of arguments i have seen on this subject seem to revolve around organic vs inorganic sourced N. I am not sure what the significant difference is beyond the ease of freeing the N and other useful ions that are subsequently freed in the process. I can see some logic to those arguments, some even backed up by experimentation such as the article on reef builders mentioned in the other urea thread comparing high levels of nitrate to ammonia and urea. From that article, I also found the following snippet intriguing:
'''
“Campbell and Speeg (1969) suggested that urea could be involved in calcification by two mechanisms: i) the neutralization of protons formed during calcification with ammonia produced by urea hydrolysis; ii) the CO2 supply to the calcification, CO2 being a product of urea hydrolysis. Crossland and Barnes (1974) also found 14C in the skeleton of corals incubated in 14C urea.” [8]

A more recent experiment solidified the idea that urea is important to coral calcification. It even demonstrated that providing corals with urea and nickel led to faster growth rates. It was found that nickel is a cofactor for the urease enzyme (the enzyme which breaks down urea), thus supplying the coral with both, allowed it to effectively metabolize urea.

“Any process which increases the supply of Ca2+ and DIC to the calcification site, or the removal of H+ from this site, will likely enhance calcification. One stimulus can be urease, which catalyzes the hydrolysis of urea to produce inorganic carbon and ammonia (Krajewska, 2009). Ammonia can help neutralizing protons emitted during the calcification process, and thus help increasing the pH at the calcification site (Crossland and Barnes, 1974). Inorganic carbon produced by urease activity can stimulate calcification directly or indirectly, via increased photosynthesis, which also requires DIC (Allemand et al., 2004; Gattuso et al., 1999).” [9]
'''

That leads me to wonder if the addition of urea in combination with ammonium bicarbonate would lead to an increase in calcification rates we would otherwise not see with the addition of ammonium bicarbonate alone. The secondary question in that vein would then also be, how much nickel is utilized in the production of urease, and is its use recyclable or would it be depleted?

 

[Poulpo]

I dosed diy urea/iron solution in my system during the last four years without any apparent problems. Initially I choose urea to not screw up ionic balance (no water change system) but I recently bought some ammonium bicarbonate after reading Randy's thought on the subject. I will certainly switch after my summer holidays. If something noticeable change I will post an update.

 

[Poulpo]

I don't get why the absence of an urea test is a problem. Even with ammonium we test for some detectable nitrate...

 

[Poulpo]

For reference, I dose 24mL per day of a 10g/L urea solution in a ~250 gallon system.

 

[Randy Holmes-Farley]

I don't get why the absence of an urea test is a problem. Even with ammonium we test for some detectable nitrate...

I don’t assume urea will accumulate, but it might. We have a long standing understanding that ammonia does not accumulate in reef aquaria, but no similar data on what happens to urea.

 

[Jari]

I have been supplementing ammonium bicarbonate (20g/l) stock solution now with urea (5g/l) for two months, and everyone seem to be happy.

 

[Bantha]

There's another thread here:

Urea-n’t Gonna Believe This!

Hey, I just wanted to get people talking about this as it's peaked my interest, I've seen people such as Randy Holmes-Farley talk about the importance of ammonia in our reef aquariums and just read this article on Reefbuilders which goes a step further into that theory with dosing urea and I...

www.reef2reef.com

My thoughts copied from that thread:

I’ve not seen many folks dose urea. Measuring it isn’t possible, so you have to dose blind in a certain sense.

It seems like it would be a fine source of N, but it may not be as useful as ammonia, because to use it, corals have to first convert it to ammonia.

Purely from an energetic viewpoint it makes sense to just use ammonia. But I think the rationale from a ecological perspective is that it is more desirable for maintaining an oligotrophic environment where corals thrive and algae and other pests not so much. Makes sense but I don't know enough about it to support that view, because some pests also thrive under oligotrophic conditions like dinoflagellates (although I'm under the impression those seem to generally thrive more under P depletion).

 

[Randy Holmes-Farley]

Purely from an energetic viewpoint it makes sense to just use ammonia. But I think the rationale from a ecological perspective is that it is more desirable for maintaining an oligotrophic environment where corals thrive and algae and other pests not so much. Makes sense but I don't know enough about it to support that view, because some pests also thrive under oligotrophic conditions like dinoflagellates (although I'm under the impression those seem to generally thrive more under P depletion).

Are you suggesting that corals can use the N in dosed urea, but algae cannot?

https://www.sciencedirect.com/science/article/pii/S0168165623000603

Microalgae is a potential source of bioproducts, including feedstock to biofuels. Urea has been pointed as potential N source for microalgae growth.

 

[Sweet Reef Corals]

Out of curiosity, what is the physiological reason to put ammonia in an SPS system? Is it to fuel more bacteria that the corals will consume or is the theory a matter of the coral using the ammonia directly?

 

[Randy Holmes-Farley]

Out of curiosity, what is the physiological reason to put ammonia in an SPS system? Is it to fuel more bacteria that the corals will consume or is the theory a matter of the coral using the ammonia directly?

Direct use is the hope, since when given a choice, those studied (which are not many) seem to prefer to take up ammonia to nitrate.

 

[reefluvrr]

Has anyone noticed deeper colors or faster growth dosing urea over ammonium vs nitrate?

 

[Red_Beard]

Not so far, but I've only been dosing it for a week now.

 

[WhatCouldGoWrong71]

Reading this thread, I wanted to add. Long story short 9 months ago my No3 was 35. Over 5 months it went to <5. I started dosing ammonia, and didn’t see much of anything. Then I started following Miami’s chart and added urea (2 months ago). I’m now up to 220 mil a day. In the last 2 weeks my No3 has finally started to come up.

My tank is very happy. But it was happy before also. I have very good PE and have insane PE at 2am. I’m still feeding 12 times a day (6 on my plank and 6 on my. AF4). System is just shy of 600g.

I will say this though. In the middle of this I swapped out my frag tank for a new one twice as big. All I did was fill it, put my racks in it and left the lighting schedule alone. Instant uglies. There wasn’t much of a CUC in that frag tank. But man, I haven’t seen GHA like that in years. I figured the ammonia was also helping fuel some of that. I added a little bit of a cuc and then after I got rid of all the GHA I added about 50 pounds of mature rock to the frag tank and now 8 days since I cleaned the tank, it looks like the algae now has something it is competing against as there isn’t much algae in that display. Good stuff.