Help with the Nitrogen Cycle

[hawkmoon]

The Nitrogen Cycle goes something like this:
Organics -> Amonia -> Nitrite -> Nitrate
(from The Saltwater Aquarium Handbook by George Blasiola)
My question is why is it necessary to test for amonia and nitrate? Why not simply test for nitrite? If you have no nitrite in the system then it stands to reason that you also have no amonia or nitrate as they are the fuel and product, respectively, of nitrite.
The reason I ask this question is that the guy at my LFS told me to only worry about nitrite when I started my tank 2 years ago. I can't say he was wrong as I had the same fish for two years with no deaths.
I read a lot of posts here quoting amonia and nitrate levels and it got me wondering if I was doing the right thing. So, what do you think? Is he right ot wrong?
Incidentily, my tank is a 24g fish only tank with 4 fish (sixline wrasse, blue damsel, clown fish & pj cardinal) and live rock.
Cheers!

 

[rs1831]

Nitrate is the end process of the cycle. So you would have to test for nitrate to make sure that its not out of control. I would also test for ammonia in case something develops in your tank and you get a spike which could kill whatever you have in your tank.

 

[hawkmoon]

If you don't have nitrite in the the system you can't have either amonia or nitrate, yes?
That's what I'm trying to determine. Does a zero or very low (< 0.1ppm) nitrite level indicate that amonia and nitrate are also absent or very low in the system?
Are all three present in the system at the same level?
I've had no problems with my tank for 2 years and have never tested for amonia or nitrate as my nitrite level is always zero or close to zero.

 

[reefnut]

No, nitrates can and usually are present with 0 ammonia and 0 nitrites... ammonia can also be present with 0 nitrites although the ammonia will be converted into nitrites.
Your tank should always read 0 ammonia and 0 nitrites after the cycle. If ammonia and/or nitrites are not 0 then there is a problem somewhere. Test your nitrates and see what they are... could be 0 or they could be off the chart.
Nitrites is just the mid-road of the nitrogen process.

 

[zsqure]

I am thoroughly confused, I began with saltwater in my 90 gal tank on May 14. I kept my temp constant at 79 - 80 deg. and my spg at 1.022 -1.023 Ph has been at 8.0 - 8.1.
On May 27 I added LS to the tank and began curing my live rock in separate rubbermaid containers in the garage. On June 14 I added LR and 2 raw uncooked shrimp. at that time the test results were...ammonia 0, trites 0, trates 12.5, ph 8.0, spg=1.022. Also there were patches of brown growth which I was told were diatoms and this was normal for a new tank. Is it normal before the tank has cycled or does it show up after the cycle is complete? My shrimp seem to be decomposing but I cannot detect an ammonia spike or a nitrite spike. I did not test everyday, every third day I tested. was my tank already cycled when I added the LR and the shrimp? my parameters and test results have been the same ever since.

 

[livephish]

my tank did the same, i actually put the water in first, then added LS, then added LR about 3 days later. my ammonia levels were off the charts- i'm talking 3.0mg/L. then two days later my nitrite was @ .8mg/L, sure enough about a day later i had to do three water changes to get my nitrates to around 10mg/L. from the time i added saltwater until the time i put the LS in was a week and half. time between LS and LR 3 days. i was figuring to have to wait like 3 weeks, nope, 4 days. i added 7 fish and the only casualties have been two damsels due to survival of the fittest- puffer ate one, and the eel ate the other, still two left......
as to the post topic... maybe you just heard wrong, maybe you thought he said nitrite, it doesn't make since, you will always have nitrates in your tank, you should never have ammonia or nitrites.... ok maybe a little but very little.... the only time you should get ammonia is with the addition of a new fish, or removing water, LR, or LS. and the only reason it is there is because you did something to the tanks bio-load. either the bacteria will die off or grow because of the ammonia present. making your ammonia and nitrite levels zero, because the bacteria is steady consuming ammonia and nitrite. the only thing you need to test for is nitrates, it takes nitrates a long time to kill a fish, you have to seriously neglect your tank, if you do that, this hobby isn't for you. i would recommend and depending on your bio-load, a weekly water change of 10-15% and check your nitrates 2-3 times a week, but testing for nitrites doesn't make since, my nitrites are always zero, and my nitrates goes from 10mg/L to about 25-30mg/L then i do a 25% water change weekly. the reason is because i have a eel, trigger, puffer, and 2 damsels, my bio-load is naturally going to be large because of the amount of food these guys consume. anyway, i hope this helps.