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View Full Version : "poof" nitrates gone, how


alanbates12
03/24/2012, 01:40 PM
OK I understand the nitrogen cycle, ammonia breaks down to nitrite which breaks down to nitrate. Then do a water change and help rid your system of nitrates.
So what would make nitrates go away without a water change, no chemicals, and no carbon dosing.
So here is my set up. It's a 180 gallon (appx 120 gallons of water) reef with a moderate bio-load. I've been running the system for almost 2 years. Recently I did buy a new tank of the same size. It has a sump, ATO, skimmer.....and I do run a carbon reactor (maybe this is the same as carbon dosing, not sure). My nitrates usually run at 0. For some reason the elevated up to 10. Which is still fine but it means I'm feeding to much or something is off on my maintenance. I bought a new CUC and made sure my skimmer was adjusted but still showed nitrates at the same level. So in the month of Feb I did 4, 40 gallon water changes and nitrates stayed the same. So I did what every reefer should do and left it alone for a couple of weeks. The nitrates went to zero. Hummmmm.
So recently I've done my regular maintenance and a couple days after, I showed nitrates again. The same level as before the water change. Had this checked also at the LFS. Left it alone for a few days and nitrates are 0. This was also confirmed by the LFS.
So my theory is that after I do a cleaning, ie: clean glass, blow off rock, vacuum sand, change out sock filters (change them every 3 days) and change 40 gallons of water my nitrates are stirred up in the system so I still get a reading for a few days. Then after everything settles the level goes back to zero. Or the system's beneficial bacterial is at a level that it takes a couple of days to catch up from me stirring up all the detritus in the system. I don't have an algae problem and everything looks very clean as you can see in the video. I' can go 3 or 4 days before I clean the glass.
So how far off is my theory?

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suphew
03/24/2012, 03:00 PM
The anaerobic bacteria in your live rock (and deep sand bed if you have one) converts the Nitrate to Nitrogen gas, so thats where it's going. It can take months for the bacteria to colonize which would be why you used to have nitrates but don't anymore.

I'd assume that since the nitrate appears in your tank after a water change, that the nitrate is in the new water. The other possibility that springs to mind is you have a deep sand bed and are disturbing it when you water change

alanbates12
03/24/2012, 03:19 PM
The anaerobic bacteria in your live rock (and deep sand bed if you have one) converts the Nitrate to Nitrogen gas, so thats where it's going. It can take months for the bacteria to colonize which would be why you used to have nitrates but don't anymore.

I'd assume that since the nitrate appears in your tank after a water change, that the nitrate is in the new water. The other possibility that springs to mind is you have a deep sand bed and are disturbing it when you water change

Tank is two years old so I'm sure the bacteria levels have had plenty of time to colonize. No nitrates in the new water. It goes through the RODI and has 0 TDS and 0 when I checked it for nitrate and p04. Sand bed is about 2 inches and this does not qualify for a DSB.

tmz
03/24/2012, 04:16 PM
When stuff gets stirred up in cleaning it can often spur degeradation and oxidation of organics that were hanging around forming some ammonia/amonium then NO2 then NO3.
The basic nitrogen cycle has 3 parts:

Ammonia oxidation to nitrite and nitrate

Removal of the oxygen by denitrifying bacteria via anaerobic activity , freeing the N to link with N forming N2(gas ) which bubbles out of the tank.

Rebinding of N from the athmosphere to H to form bioavailable fixed nitrogen like ammonia by bacteria capable of breaking the N2 bond alowing N to join up with H.

Cyanobacteria and related diazotrphs are uniquely able to do this with an enzyme they produce known as nitrogenase.

So round and round it goes .

bertoni
03/24/2012, 06:49 PM
I agree that the cleaning process can dump nutrients into the water column. Vacuuming the sand could reduce its filtration capacity a lot, for example, depending on what's done.

alanbates12
03/26/2012, 12:06 AM
Still looking for more info