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Old 05-01-2013, 12:40 AM   #1
meppitech
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CO2and cycling


With no fish in my tank, i have increased my co2 to where i have seen the plants respond in a very positive way, but I have seen a weird turn in my cycle. My nitrates were off the charts and then just dropped to zilch one dayl, but where ammonia was being consumed at a rate of at least 2ppm per day, it is only getting rid of about .5 per day and nitrates are on the rise slowly again. In the meantime i also switch to dry EI dosing. My nitrates were somewhere over 80 before my weekly waterchange. So i dont know if high nitrates might do this, if the plants prefer nitrates to ammonia, or if it is the co2. Lastly my tap water is 7.6 and i tested tonight and it registered the lowest my test goes (6). Any help is greatly appreciated. Thanks. Ooh. Here is a pic for the heck of it. I know it is scattered. I was just trying to grow things out a bit before placing them where they will be scaped in.

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Old 05-03-2013, 08:28 AM   #2
Lupine
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First let me say, I found your post because I have the same kind of problem and was looking for an answer. After changing CO2 canisters, my regulator became difficult to set just right. I wound up flooding my nano w/CO2. As the drop checker turned yellower, the Ammonia Alert tag I have in the tank went from showing 0 NH3 to 0.2 ppm. There are no fish in the tank.

Having found no answer to the issue, I googled CO2 and NH3. After reading several journal papers on industrial CO2 emissions and NH3 which are way over my head, I have seen that there is a definite correlative relationship between NH3 and CO2, the more CO2 you have, the more NH3 can be produced. Also, I found this handy-dandy equation which I'm sure would explain it if it weren't 3AM and I was coherent enough to rearrange the factors to show what occurs in the aquarium:

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

My understanding is that the equation would show (if you reverse it) that when you put CO with H2O and some source of N, you will get NH3 as a byproduct. I guess it's just not a relevant amount in the aquarium unless you overdo it on the CO2.

If you don't have a drop checker or other CO2 test, get one. There's no need to waste CO2 if you're dosing too much like I accidentally did. If you're not overdosing CO2, maybe you have too much N from ferts?

Hope this helps. If someone else has a better explanation of the CO2-NH3 relationship, please chime in!
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Old 05-03-2013, 01:07 PM   #3
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Quote:
Originally Posted by Lupine View Post
First let me say, I found your post because I have the same kind of problem and was looking for an answer. After changing CO2 canisters, my regulator became difficult to set just right. I wound up flooding my nano w/CO2. As the drop checker turned yellower, the Ammonia Alert tag I have in the tank went from showing 0 NH3 to 0.2 ppm. There are no fish in the tank.
There may be a better explanation for the ammonia showing up. First of all, are you adding any ammonia? It is unlikely that ammonia will just "appear" out of nowhere (it may be possible that high CO2 levels cause some bacterial die off, causing a mini-cycle and a small increase in ammonia levels).

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Originally Posted by Lupine View Post
I have seen that there is a definite correlative relationship between NH3 and CO2, the more CO2 you have, the more NH3 can be produced.
Where is the ammonia coming from?

Quote:
Originally Posted by Lupine View Post
Also, I found this handy-dandy equation which I'm sure would explain it if it weren't 3AM and I was coherent enough to rearrange the factors to show what occurs in the aquarium:

2NH3 + CO2 --> (NH2)2CO + H2O
This is not a thermodynamically favoured reaction. Ammonium bicarbonate is not made so easily in aqueous solution.

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Originally Posted by Lupine View Post
My understanding is that the equation would show (if you reverse it) that when you put CO with H2O and some source of N, you will get NH3 as a byproduct.
No, this is incorrect. You will not get ammonia as a byproduct by adding carbon monoxide with water and a source of nitrogen.
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Old 05-03-2013, 02:24 PM   #4
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i dont see bacteria dying as co2 is added. they just go in remission/ stasis so to speak, waiting for parameters to come to more of their liking.

nitrogen conversion slows as ph drops due to co2 injection
nitrogen fixation stops completely around 5.8 ph.

so this explains when ammonia is not being handled well,
hungry plants can consume a decent amount of nitrates in one day's time, especially if the addition of carbon is recent.

id say things are pretty normal for your tank, and as bacteria continue to grow, ammonia will get handled.

i would not however run co2 24/7 there needs to be an off period to allow bacteria to do their work.
ammonia also has to be added. it doesnt show up.
rotting leaves, fish food, poop which u dont have
etc. co2 and aquarium water dont generate ammonia
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Old 05-03-2013, 07:31 PM   #5
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I am not adding any ammonia and have no fish or rotting plants they are all doing very well. I did have nitrates the last time I checked from the tank being toward the end of its cycle. Since I'm not adding fish soon I hadn't checked it recently. But I figured according to what I found in my online search that the NH3 came from the addition of too much CO2 to H2O with NO3 in it. This is the only explanation I could find for why NH3 would "come out of nowhere". I am no chemist obviously so I do not know if this process which was described as a means to convert industrial CO2 emissions would happen in an aquarium. Neither myself nor the OP as far as I can tell have in any way been adding NH3. But it appeared after increasing CO2. I thought I was on to something with my findings last night, but clearly not. My pH is 8.10 according to the probe because I started with my very alkaline well water. Maybe the OPs pH is too low for nitrification, but mine is not, and I don't mean to be argumentative or a hijacker, I originally posted as a means to try to help or at least get things rolling, so we're back to the original question, how does increased CO2 increase nitrates or ammonia? I get from the other replies that it shouldn't, but I think there's evidence here from the OP and myself that it does, or maybe I'm just really hard headed?
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Old 05-03-2013, 08:17 PM   #6
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well put simply
i inject enough gas to drop my ph 1.4 degrees. and nitrates hover around 60-80 ppm
i have no ammonia in my tank.
so the question would be why does it not happen to me, or every other hobbyist?
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