DIY Urea + Ammonia Mix Dosing Chart

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@Randy Holmes-Farley

Question:
My tank has found stability. I got my nutrients in order. A year ago I had no No3 and low PO4. After 5 months of fighting that I started dosing ammonia. I have a high density SPS system with insane lighting (600 par in the sand) and 150 times display turnover. I also have been feeding 12 times a day for almost a year. My PO4 is 0.10 and No3 is 10. I have had some random STN/RTN for about 2 months now. I’m stressing my coral out so I am slowly removing things (UV, Ozone, taking Par down, shortening my Halide time and shortening my over all time slightly). I’m also winding down Ammonia dosing. I stopped increasing my ammonia dosing amount about 4 months ago and have been hovering at 180 mil a day for 4 months. I followed the chart here and it worked as my nutrients came up and got stable. However, I have too much ammonia in my tank for my comfort.

To me it looks like I am 3x’s the limit (of Aquabiomics recommendations). Are the amounts listed in my test alarmingly high?


Screen shot of the area in question. Links for both Aquabiomics attached also.

https://aquabiomics.com/wp-content/uploads/simple-file-list/reports/TheDryReef/1002385_tankDNA.html
https://aquabiomics.com/wp-content/...st/reports/TheDryReef/1003650_microbiome.html
 

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Unfortunately Miami Reef won't be here for my most recent observations regarding urea/ammonia (😭) but the project continues:

I temporarily stopped dosing any nitrogen containing solution per Miami's recommendations as my nitrates were reading between 15-20. Over the course of around a week, things started looking pretty poopy. My toadstool and grubes gorg were extremely ticked. I noticed many corals expelling zooxanthellae at peak light level/mid day, as well. Nitrates began to trend down after stopping all dosing. Because things were looking so unhappy, I decided to put some ammonium bicarbonate back on, sans urea, at a much lower rate than I originally was using (6mL per day, I was up to 27/day previously.).

Things are coming around...the grubes and toadstool are coming back out, but nitrates are continuing to trend down (currently at 5ppm.) I'm going to try an ammonium and urea combo again, but at a lower urea level. I'm actually thinking as low as 1g/L urea to start.

One other observation to add: I mentioned previously that I had severe blinding over of my filter socks (mesh, not felt) when I started the ammonia dosing. This has continued to be the case - it ceased when I temporarily stopped, and recurred after starting the ammonia.

How is the lower dose of urea working for you? I actually did exactly the same switch around the same time as your post (mainly due to darkening of SPS and nitrate getting higher), and find that 1/10 urea to ammonium bicarbonate works much better (at least anecdotally). Currently dosing (only) 3ml per day which keeps the nitrare around 20 (phosphate 0.15-0.25).

When I started ammonium dosing roughly two years ago, I had to dose 20-30ml using Randy's OG ammorecipe to keep the nitrate levels around 10.
 
@Randy Holmes-Farley

Question:
My tank has found stability. I got my nutrients in order. A year ago I had no No3 and low PO4. After 5 months of fighting that I started dosing ammonia. I have a high density SPS system with insane lighting (600 par in the sand) and 150 times display turnover. I also have been feeding 12 times a day for almost a year. My PO4 is 0.10 and No3 is 10. I have had some random STN/RTN for about 2 months now. I’m stressing my coral out so I am slowly removing things (UV, Ozone, taking Par down, shortening my Halide time and shortening my over all time slightly). I’m also winding down Ammonia dosing. I stopped increasing my ammonia dosing amount about 4 months ago and have been hovering at 180 mil a day for 4 months. I followed the chart here and it worked as my nutrients came up and got stable. However, I have too much ammonia in my tank for my comfort.

To me it looks like I am 3x’s the limit (of Aquabiomics recommendations). Are the amounts listed in my test alarmingly high?


Screen shot of the area in question. Links for both Aquabiomics attached also.

https://aquabiomics.com/wp-content/uploads/simple-file-list/reports/TheDryReef/1002385_tankDNA.html
https://aquabiomics.com/wp-content/...st/reports/TheDryReef/1003650_microbiome.html

I cannot see a reason to be concerned about elevated nitrifiers in a tank dosing ammonia. That would be expected, IMO.

I might wish they were not there so corals get first shot at the ammonia, but cannot see how they are causing a problem.
 
Going to start dosing this in my classroom reef. The beauty of being a science teacher is that there are always bulk quantities of these compounds lying around.

My mangrove and macro-algae growth just strips out just about all PO4 and NO3, regardless of how much food I add. Current PO4 is 0.03ppm, and NO3 looks to be about 2ppm.

I just did a massive rehab project on the tank and really did some damage to the mangrove roots. They dropped a bunch of leaves but that has leveled off. I also redid the macro tank the other day and pulled several pounds of Caulerpa. So those two things are probably giving me the NO3 and PO4 bumps that I’ve seen, because it’s usually much lower.

Once the mangroves and macros start growing back, I expect those #s to bottom out. So I am going to start dosing urea/ammonia bicarbonate tomorrow and see if I can keep the NO3 level up through the regrow.
 
All I have on hand is ammonium carbonate. Dose a lower volume?

Do you have a link to it? Strictly speaking one would dose less, but some sellers may use that name interchangeably with ammonium bicarbonate.
 
I cannot be sure if that name is correct, but if it is, you would use 0.6 times as much as the recipe here for ammonium bicarbonate. At the end of the day, it doesn’t
matter much since you will adjust dosing based on nitrate or tank appearance.
 
I cannot be sure if that name is correct, but if it is, you would use 0.6 times as much as the recipe here for ammonium bicarbonate. At the end of the day, it doesn’t
matter much since you will adjust dosing based on nitrate or tank appearance.
Thanks Randy. I figured I would check before I dumped twice as much ammonia in as I should. I’ll dose @ 0.6x, and if it’s not raising the NO3, I’ll nudge the dosing up.
 
How is the lower dose of urea working for you? I actually did exactly the same switch around the same time as your post (mainly due to darkening of SPS and nitrate getting higher), and find that 1/10 urea to ammonium bicarbonate works much better (at least anecdotally). Currently dosing (only) 3ml per day which keeps the nitrare around 20 (phosphate 0.15-0.25).

When I started ammonium dosing roughly two years ago, I had to dose 20-30ml using Randy's OG ammorecipe to keep the nitrate levels around 10.
Sorry for the slow response, I am not on here much.

Lots has transpired since I posted about my urea addition. I actually got fed up with the urea and went away from it altogether. I had played around with my ratio of ammonium to urea nitrogen contribution in the stock solution, and it just seemed so hard to control. I really wanted to end up in the "safe zone" of 5-10ppm of nitrate. I decided to go away from the urea and started using a small amount of Neonitro in it's place. I use 4.4g/L of ammonium bicarbonate and 30mL/L of Neonitro as my "stock solution".

Until pretty recently I was dosing 5mL x 6 times a day (my total water volume is around 65 gallons) but recently increased that to 10mL x 6 times a day. My tank started to have a bit of a growth spurt and my nitrates had trended down from 5-10ppm on Salifert to more like 2ppm. Today is only day three of evaluating the increase in the amount being dosed.

I have not seen any negatives of quickly increasing solution addition rate - only the other way around. I effectively doubled my dose in a single day this week and everything looks wonderful so far. My one word of caution is that it seems like corals get accustomed to having their nitrogen "fed" to them in a certain form. Certain corals have gotten extremely ticked when I transitioned away from what I think are the more easily metabolized forms (ammonium and urea towards nitrate).
 
This is a freshwater article, but as more folks experiment with urea, it will be interesting to see if any get problem cyano:

https://pmc.ncbi.nlm.nih.gov/articles/PMC6536089/
"Urea has been linked to cyanobacterial blooms as it is a readily assimilated nitrogen (N) - source for cyanobacteria that possess the enzyme urease. "
i have not done urea dosing so far (will try now), but i have constant low nitrate in my tank - when it's too low i add no3 or ammonium (ati nutrition n or other known suppliers) and i always encounter cyano bloooms afterwards. that experience is kinda consistent since 2-3 years. and there seems to be no difference if i add no3 or ammonium
 
i have not done urea dosing so far (will try now), but i have constant low nitrate in my tank - when it's too low i add no3 or ammonium (ati nutrition n or other known suppliers) and i always encounter cyano bloooms afterwards. that experience is kinda consistent since 2-3 years. and there seems to be no difference if i add no3 or ammonium

Well, the cyano/urea experiment will be interesting, but many cyano can readily use urea as both a nitrogen and carbon source.

https://pmc.ncbi.nlm.nih.gov/articles/PMC6536089/
 
One of the big problems that I've had with the ammonium bicarbonate/urea dosing is the off gassing (I'm guessing CO2) and big air bubbles forming in my dosing lines. Since I'm micro dosing small amounts throughout the day, sometimes the doser will go off and nothing will get dosed because of the gas in the tubing. I've tried clear, solid and blue dosing containers and it makes no difference.

I've since switched back to sodium nitrate on the same doser and I don't have that issue anymore so I know the dosing lines are sealed well. Would using the ammonium chloride get rid of the off gassing? Honestly I haven't noticed much of a difference from the ammonium/urea and the nitrate. I do feed frozen and pellets pretty heavily, so I'm sure there is plenty of ammonia getting in that way already, just not enough to keep my N measurable without the sodium nitrate.
 
One of the big problems that I've had with the ammonium bicarbonate/urea dosing is the off gassing (I'm guessing CO2) and big air bubbles forming in my dosing lines. Since I'm micro dosing small amounts throughout the day, sometimes the doser will go off and nothing will get dosed because of the gas in the tubing. I've tried clear, solid and blue dosing containers and it makes no difference.

I've since switched back to sodium nitrate on the same doser and I don't have that issue anymore so I know the dosing lines are sealed well. Would using the ammonium chloride get rid of the off gassing? Honestly I haven't noticed much of a difference from the ammonium/urea and the nitrate. I do feed frozen and pellets pretty heavily, so I'm sure there is plenty of ammonia getting in that way already, just not enough to keep my N measurable without the sodium nitrate.

Ammonium chloride may reduce the offgassing. I have not noticed it myself.

Are the bubbles before or after the pump? Maybe too much negative pressure as the pump sucks up fluid leads to bubble formation between it and the reservoir.
 
Ammonium chloride may reduce the offgassing. I have not noticed it myself.

Are the bubbles before or after the pump? Maybe too much negative pressure as the pump sucks up fluid leads to bubble formation between it and the reservoir.
They’re both before and after the pump. Like I said I’m using the same pump and lines to dose a sodium nitrate/sodium phosphate solution and I don’t have the bubbles at all. It’s just when I use the ammonium bicarbonate, which is why I assume it’s CO2 forming.
 
They’re both before and after the pump. Like I said I’m using the same pump and lines to dose a sodium nitrate/sodium phosphate solution and I don’t have the bubbles at all. It’s just when I use the ammonium bicarbonate, which is why I assume it’s CO2 forming.

Might be that, but I’ve not heard of it happening before. What brand of ammonium bicarbonate?
 
They’re both before and after the pump. Like I said I’m using the same pump and lines to dose a sodium nitrate/sodium phosphate solution and I don’t have the bubbles at all. It’s just when I use the ammonium bicarbonate, which is why I assume it’s CO2 forming.

Might be that, but I’ve not heard of it happening before. What brand of ammonium bicarbonate?
This one from Amazon.
20260625_124932_4475CCFB-7EC1-4587-AD21-A2D4DDA40C0B.png


20260625_124932_4DD2DC2F-BE12-4506-9490-2ACED3E6A612.png
 

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