# Plant trimming = nitrate spike?



## Linwood (Jun 19, 2014)

I had a lot of nitrates once AFTER a water change, which involved a lot of substrate vacuuming, and a bit of rearranging as well as trimming of plants. I still don't know quite why, but I wonder if stirring up the substrate exposed either high nitrate water, or some partial decay that then finished decaying rapidly (and cycled). 

In a different tank I regularly take out a huge amount of wisteria - like double handfulls, that represent maybe 30% of the plants -- and see no spike.

Sorry, not really an answer I know...


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## micheljq (Oct 24, 2012)

Trimming, playing in the substrate, may have the effect of leaching ammonia in water, which finally turns into nitrates. Stems are cut, leaching in water, if substrate is stirred, same overall effect. Photosynthesis is affected.

That's why people often do a good water change the same day.

Michel.


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## Raymond S. (Dec 29, 2012)

The plants do use ammonia first and then nitrates so lowering the amount of them increases the amount that is left in the tank because of not so many plants are using it as much as before the trim. It doesn't really explain that high of a test though. 
You might also consider that if you are dosing KNO3 and the level of plants that you had was using it all up and then you lowered the amount of plants, it now doesn't use all the NO3 in the doses you are using which I presume would raise the nitrate level in a test. Just trying to think of any contributing causes...


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## fishbone11 (Sep 11, 2014)

Raymond S. said:


> The plants do use ammonia first and then nitrates so lowering the amount of them increases the amount that is left in the tank because of not so many plants are using it as much as before the trim. It doesn't really explain that high of a test though.
> You might also consider that if you are dosing KNO3 and the level of plants that you had was using it all up and then you lowered the amount of plants, it now doesn't use all the NO3 in the doses you are using which I presume would raise the nitrate level in a test. Just trying to think of any contributing causes...


 Raymond, you may be on to something. The substrate had minimal disturbance. I tweeze planted only two items. My ferts are PPS - Pro which is a low dose method. When the plants were at the now trimmed stage, they received the same dose without high nitrate readings.
But, I may hold back on the ferts for a few days to see what happens to the readings.
Today's readings have increased again (higher than the post water change numbers). So whatever is going on, it's still going on.


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## fishbone11 (Sep 11, 2014)

Reading for nitrate has returned to normal and started the ferts after holding back one day.
All is good again.
Thanks


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## tylergvolk (Jun 17, 2012)

I recently did a major trim cutting back 90% of my heavily planet 125 gallon tank. I failed to dial back the fertilizer and the CO2. As a result, I lost several fish in the process due to dangerous CO2 levels and nitrate levels. I learned the hard way to adjust the CO2 and fertilizer to be in line the plant growth rate. See after a trim, that plant doesn't grow at the rate it did before the trim.

Key point: focus on plant growth.


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## jbig (Jul 13, 2012)

+ 1 to everything raymond said. I had a 20g long that eventually turned into a heavily planted wisteria jungle. after I would do heavy trims nitrates would spike. eventually I took all the wisteria out and had to stop dosing nitrates because it was way too much. I believe water wisteria are nitrate hogs as well. So when you trimmed you're wisteria you probably lost a lot of plant mass that was absorbing your nitrates.


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