Fishless Cycling With Biomature - Daize's Log

[daizeUK]

I love chemistry!

I think I understand what you are saying, i.e. the nitrogen atom is preserved regardless of what it bonds with. You can't create or destroy nitrogen atoms (at least not in a fish tank

) so only one nitrite ion or nitrate ion can be created for every original single ammonia molecule. Therefore a 1:1 relationship in terms of molecules.

However I don't follow if that translates directly into parts per million measurements. Eagle spoke in terms of molecular weights, therefore one nitrite ion still has more 'weight' when it is measured as parts per million than the original ammonia molecule - is that right?

 

[eaglesaquarium]

I'm always willing to learn more, so I'd like to discuss this further, if possible.


My understanding is that 1ppm is equivalent to 1 mg/L, since the solvent is water. So, the increase in mass of the molecule that we are measuring due to the introduction of the oxygen atoms to the Nitrogen means that the molecule we are measuring is more massive, so the 1:1:1 ratio for the NITROGEN, shows up at different values of PPM, because the MOLECULE that we are measuring is much heavier than the original molecule.


The link isn't working for me on my computer right now, so I'd like to hear where I am mistaken more specifically. Do the solutions in the test kit actually measure the NITROGEN, or are they measuring the entire molecule? Since they are measured in PPM, I would assume its the entire molecule, but I could be mistaken.

 

[TwoTankAmin]

see the top 3 posts here http/www.cichlid-f...c.php?p=1748392

take a look here next http/nitrification.org/

 

[eaglesaquarium]

Quoted from the first link... Dr. Tim.

Ok, that test kit measures in the ion form. When I say 5 mg/L-N I mean ammonia-nitrogen or nitrite-nitrogen not in the ion form.

3 ppm ammonia in the ion form -- your kit, equals roughly 2.2 ppm ammonia-nitrogen (divide the ion value by 1.216 assuming your measure NH3-ion)

3 ppm nitrite in the ion form -- your kit, equals roughly 1 ppm nitrite-nitrogen (divide the ion value by 3.284)

What this means is that in the units I discuss your values are less than what you may think. I would wait 24 hours and them re-measure and then re-dose

Its been a long week. Can you explain this a bit more slowly. The numbers to divide the ion value by are coming from what exactly? I'm just not able to concentrate right now...

 

[daizeUK]

A man of few words but many links! I'm actually a little hazy on whether TwoTankAmin is saying that Eagle is wrong or just pointing us towards some interesting dissertations on water biochemistry for our intellectual stimulation!

Since 1 ppm ammonia-nitrogen must be converted to 1 ppm nitrite-nitrogen then Dr Tim's calculations can be expressed another way by saying that 1ppm ammonia molecule will be converted to (3.284 / 1.216) = 2.7 ppm nitrite-ion, which agrees exactly with the numbers Eagle was using... just using a different measurement of calibration!

However further down the thread the same Dr Tim says this : " The conversion is that 1 ppm of the nitrite-nitrogen equals 4.4 ppm of the nitrite ion." I don't understand where he gets this from because earlier he uses a 3.284 conversion factor?

Another interesting thing I picked out of this is that over-use of dechlorinators can slow down the nitrification process. That's important since I was considering overdosing it to be on the safe side.

 

[daizeUK]

Eagle - I hope you understand what I meant? Dr Tim's numbers are simply molecular weight ratios using Nitrogen as a base reference. I can try to explain...

He's saying that 1ppm Nitrogen is equivalent to 1.216ppm Ammonia, since the molecular weight of NH3 is 1.216 times greater than the atomic weight of Nitrogen.
[Proof: The atomic weight of nitrogen is 14 (that's 7 protons + 7 neutrons). The atomic weight of hydrogen is 1. Add them up and the molecular weight of Ammonia NH3 is therefore 17. So that's where Dr Tim gets his numbers from, since 14 * 1.1216 = 17]

Similiary, 1ppm Nitrogen is equivalent to 3.284ppm Nitrite, since the molecular weight of NO2 is 3.284 times greater than the atomic weight of Nitrogen.

Since the nitrogen is conserved throughout the cycle, you will always have the same concentration of Nitrogen whatever form it takes. Here's an example:
I start the cycle by adding 5 ppm Ammonia NH3 to my tank. Therefore my Nitrogen concentration is (5 / 1.216) = 4.11 ppm.
Then the nitrifying bacteria convert all the ammonia to nitrite NO2. I must still have a concentration of 4.11 ppm Nitrogen, since the nitrogen hasn't gone anywhere, therefore my Nitrite concentration is (4.11 * 3.284) = 13.5ppm.

Now if you notice, the nitrite concentration is (13.5 / 5) = 2.7 times the original ammonia concentration, so your numbers are perfectly accurate too. Dr Tim's numbers are simply an alternative way of going about it, since he prefers to work in terms of nitrogen concentrations. It seems that some test kits will measure nitrogen concentrations, but the API test kit doesn't so we can forget about nitrogen and talk in terms of ammonia and nitrite ion concentrations instead.

In summary, I don't think there's any disagreement here, it's simply different ways of measuring the same process and depends what test kit is being used. Nitrogen concentrations are fairly irrelevent to us, except that it's always nice to have a deeper understanding of the chemistry!

 

[eaglesaquarium]

Ok. Its was a late night last night and my son was starved for attention, so I couldn't really concentrate... I'm a physics teacher, so I have a fairly decent chemistry background (basics) and I just wasn't seeing where what I had said was incorrect. It was late though, so I wasn't sure if it was me or not. ;-)

 

[daizeUK]

I thought you might understand it better than me It's been about 20 years since I touched this stuff at school, so I'm amazed it made as much sense to me as it did.
Always loved science. I wanted to have a career change and become a physics teacher when the kids are older, but i doubt it will ever happen.

 

[TwoTankAmin]

I would like to continue this discussion, but this thread has already been hijacked enough. I think further discussion would be more appropriate in a separate thread in the scientific section.

 

[daizeUK]

By all means start a new post, I'll be interested to read it.

To get back on track, a small update; I emptied the tank today and started over, since my cycle was going nowhere. Added a few fish flakes into the filter as suggested and redosed with BioMature and a large dose of Filter Start. I'll post back in a week or so with results.

 

[David J]

Good luck Daize. I'm sure it'll work this time. Think of all you've learnt.

 

[daizeUK]

Thanks