Nitrogen Cycle Chemistry Question

[cvermeulen]

Okay, this may wind up being long winded... but here goes.

NH3->N02->NO3, right? so far as I can tell, 1mg of ammonia will make 1mg of nitrite which will in turn make 1mg (or say 1ppm) of nitrate.

SO. When I'm going through my cycle... right now, if I do a large water change, the next day I will pretty consistently have 0.8ppm nitrite, and 20ppm nitrate. I am power feeding some messy fish, so the high numbers don't surprise me... my question is this:

The bacteria colony in the filter must be processing 20ppm of nitrIte to get 15-20ppm of nitrAte, right? and there is 0.8ppm left over because they are not completely established yet... but the way I read that is they are only missing about 5% of the nitrite... so shouldn't this mean I'm 95% of the way there? what is going on? why is that last 5% taking so long? am I missing some large bit of chemistry here?

 

[12 Volt Man]

it doesn't necessarily mean you are 95% there.

it means that you are 95% there today.

not necessarily tomorrow.

your fish eat a bit more tomorrow, excrete a little more ammonia through their gills and you may not be 95% there tomorrow, if you know what I mean.

it is a dynamic system.

however, your bacteria should be reproducing too, so as the first food source for them goes up (ammonia), their population should go up a bit too in these early stages.

the other thing is that you may have more nitrosomonas (the ammonia oxidizers) than you do nitrobacter (the nitrite oxidizers), so you can have more ammonia than you do nitrite.

its not always a 1:1 ratio.

hope this helps you a bit..

for now, just keep doing what you are doing (not overfeeding and do water changes) and eventually your tank will build up enough of a population such that the ammonia and nitrite are being broken down as quickly as they are being produced (so you get 'unreadable' levels when you test) and your tank will be stable and 'cycled'

then, its just a matter of keeping the (aquarium) end product, nitrate, down through normal weekly water changes.

 

[ewurm]

I would add an established filter or established media to the tank when you cycle. That would eliminate this question completely.

 

[cvermeulen]

I would add an established filter or established media to the tank when you cycle. That would eliminate this question completely.

Thanks but... oh nevermind.

 

[cvermeulen]

it doesn't necessarily mean you are 95% there.

it means that you are 95% there today.

not necessarily tomorrow.

your fish eat a bit more tomorrow, excrete a little more ammonia through their gills and you may not be 95% there tomorrow, if you know what I mean.

it is a dynamic system.

Well okay... fair enough. I actually fed LESS the last two days than the previous days before that... I seem to have a pretty consistent 0.8ppm reading though. maybe my gravel vac isn't what it could be, or there's decaying food in my filter bags (that are getting cleaned today).

however, your bacteria should be reproducing too, so as the first food source for them goes up (ammonia), their population should go up a bit too in these early stages.

the other thing is that you may have more nitrosomonas (the ammonia oxidizers) than you do nitrobacter (the nitrite oxidizers), so you can have more ammonia than you do nitrite.

I'm sure I have more NH3 oxidizers, they are the first to develop, and my ammonia is always unreadable (0) lately.

I know eventually it will sort itself out, I was just confused, conservation of mass and all, it seems like the tank is processing WAY more nitrite than it's not processing, so I wondered why that last little bit would be taking so long.

I also used bio spira in this tank. Maybe it worked 90% of the way and the bacteria is just having to reproduce to make up the remainder.

 

[ewurm]

I also used bio spira in this tank. Maybe it worked 90% of the way and the bacteria is just having to reproduce to make up the remainder.

You said you are power feeding, I suspect that the bacteria from the Biospira couldn't keep up.

 

[12 Volt Man]

agreed. powerfeeding is not good for a tank that is still cycling..

try cutting back and your system should stablize much faster.

good luck!

 

[mosthated]

what you feeding anyways?

 

[fishdance]

If you have a look at this chart showing the nitrogen cycle you will see there are peaks of Ammonia, then Nitrite and finally Nitrate along with approx time for this to occur which is usually 4 -6 weeks.

http://research.yale.edu/peabody/CICHLID/MO/n-cycle.gif

If your within this timescale then this is perfectly normal and a GOOD thing since you have to go through the peaks to get to established nitrosomas and nitrobacter populations. The chart shows how you can have ammonia and nitrite at the same time and what to expect.

If you are getting ammonia and nitrite levels beyond this time scale then you have a biological filtration problem. Either insufficient biological filtration, overfeeding, overstocking or some other cause. But it sounds like your in your cycle period and just (naturally) impatient.

There is a lot of info online so do some research and post any specific questions you might have. Lots of very knowledgeable people here willing to help out.

 

[aropal]

Don’t forget your fish excrete ammonia as a product of their respiration, it’s not all rotting food and poo.
So even if you stop feeding them and clean all the waste out of their aquarium you will still get ammonia while the fish live.

The reason it takes more time to get rid of that last little bit of nitrite may well be that the lower the levels the slower the rate of reproduction of those bacteria using it as a food source. So, bacteria are sustaining their population but not increasing it at quite the same rate as they started. If they always continued at the same, initial, rate of reproduction they would have population crashes as they ran out of food (nitrite in this case). My guess is that free nitrite is limiting in the reproductive rate of nitrite consuming bacteria.