Nitrogen Cycle Diagram

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aklaum

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Dec 31, 2005
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I just wanted to post a diagram I made of the Nitrogen Cycle. I wanted something to use to explain this to my 7 year old son. The new 20 gallon tank was his Christmas present.

I'm new at fishkeeping as well so let me know if you see any inaccuracies and I will fix them and repost. My son liked this diagram so I hope it is useful for others.

Here is the the link to the diagram:

Nitrogen Cycle Diagram
 
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As applied to standard hobby tank, that is not bad. But the nitrogen cycle is a great deal more than that in reality. Nitrogen-fixing microbes take gaseous N2 from the air and convert it to a combined form which is useful to plants and later to animals. Nitrogen may take multiple pathways through plants and or animals and be incorprated into their tissues. Eventually the dead plant or animal, or their nitrogen containing waste, is processed by specialized microbes back to gaseous N2 and returned to the atmosphere. That is what makes it a cycle, it is a huge variety of loops, all starting with N2 gas from the air, and eventually all returning to N2 gas in the air. In tanks we only see a a small part of one particular loop.

It is risky to say that the either ammonia or nitrite is more dangerous. On a nitrogen basis, the nitrite is far more deadly N for N, but also ammonia exists in two forms in water - the ammonium ion which is effectively harmless, and the dissolved gas NH3 which is quite toxic. IMHO it is better just to consider both harmful and potentially deadly without assigning any relative danger to either.
 
So perhaps change the title to:

Nitrogen Cycle in Freshwater Aquariums

and make both Ammonia and Nitrites equally deadly?

Also, I noticed I put "Keeping Nitrates under 50ppm is usually sufficient". Now for some reason I'm thinking 20ppm? I've read so much the past few months I can't remember anymore.

By the way RTR, I wanted to say how much I appreciate your input on these posts. From what I have seen of your sizeable number of tanks, you don't exactly have hours and hours of free time to answer newbie questions. I could see getting to a point in the hobby where you are so busy with the hobby itself that it becomes difficult to find time to share your knowledge. I certainly appreciate that as involved as you are you take the time to answer these questions so quickly and completely.

Just my 2 cents.
 
I'd say it depends on your "base levels." If out of the tap (or well) your nitrates are 35ppm, there's no way you'll be able to maintain a <20ppm nitrate level. 50-60ppm would be decent for such a situation...though not healthy for the more sensative species of fish.
 
I'd say it depends on your "base levels."
Click to expand...

I tend to agree with this statement, for the purpose of the chart I would almost say don't put a number on it. for most folks with a tarting point of 0 20-30 ppm is the target. Nitrates themselves have to be fairly high to actually be toxic. But they are the easy test that shows us how quickly pollutants build in a tank. SO if we do enough water changes to control nitrates, we are also controlling other pollutants we cannot easily test for.

When you get the diagram the way you like it, you should feel free to post it on the cycling article if you so chose. It could benefit some people I'm sure. I've always thought if I opened an LFS I'd post something similar on the wall for customers to see.
Dave
 
Thank you all for the feedback. I have modified the diagram. Here is the new version.

Nitrogen Cycle Diagram 2

daveedka, I would be honored to post it on the cycling article once it is complete.
 
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