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Hawkian 12-08-2009 03:01 PM

Nitrites... after the cycle?
Uummm... is it normal for nitrites to start climbing again after the cycle is completed? :shock: I have been monitoring the tank weekly since the cycle finished (2 months ago) and ammonia and nitrites are always '0'... except for today. They are low (0.1 mg/L) but why are they even there is what I'd like to know!!!! Is this normal? Can adding plants to a tank spike up the Nitrites (seems unlikely to me)? Can me cleaning my filter with aquarium water cause this? Can adding substrate cause this?

To start from the beginning here, yesterday I added 2 KG of substrate to my 32g, as well as some plants. The day before that I had done the weekly maintenance (20% wc, syphon gravel, etc.).

Byron 12-08-2009 04:22 PM

As many of us have written, once a tank is established the readings for ammonia and nitrite should remain at zero unless something occurs to alter the nitrification bacteria/cycle. This is in a non-planted tank, which includes a tank with too few plants to handle the ammonia and nitrite. In a fairly-heavily planted and biologically balanced tank, one should never experience ammonia or nitrite above zero.

Adding plants will not increase nitrites; quite the opposite if nitrite is present. However, both cleaning the filter and/or changing the substrate can cause a mini-cycle--in a non-planted tank. If you removed the former substrate, then you removed an incredible colony of bacteria with it. I suspect this is the reason, since you mention cleaning the filter with tank water which should not have removed too much of the bacteria. If the tank was well planted previously and the plants went back in, there would have been no mini-cycle from doing either or both of these things. The nitrification bacteria colony in a plante3d tank is minimal since the plants do the majority of nitrification and are faster at grabbing the ammonia than are the bacteria.


Angel079 12-08-2009 05:19 PM

"Messing" with your filter would do that. From the sounds of it you're doing too much cleaning there with your filter IMO and in doing so you're destroying the beneficial bacteria. So quit messing with the tank :-)

And/ or only having few plants and maybe (you only can know that not me) you're also feeding your fish too much > Too much left overs > Too much food - Too little w/c in comparison to the waste....that's all factors that'll do it.

Hawkian 12-08-2009 07:24 PM

All right... looks like I'll need to watch out for a few things in the future. And here I thought I was an expert b/c my tank cycled without any hiccups the first time arounf! ;-)

Thanks a bunch!

Angel079 12-08-2009 08:12 PM

Less is more in the tank world :-)

Less foods, less man-made 'fussing around' in there, less see where I'm getting at :-)

How does this saying go..."Let well enough be!?"

1077 12-09-2009 04:40 AM

In my own tanks,(no plants) I try to space out the maint so as not to do too much at one time.
One week, I will vaccum the substrate perhaps one third while doing a water change. The next week another one third, and so on. The next week, I will service the filter ,( have two on all tanks). The next week I will service the other filter and this prevents me from going hog wild with cleaning, and destroying too much bacteria at one time. I am near anal about water quality and if I don't exercise some control.. I tend to clean a little too much at once.:roll:

Hawkian 12-14-2009 11:16 AM

OK so mini-cycle finished! Nitrites never went higher than 0.1 mg/L and Nitrates never higher than 10 mg/L. All I ever did was do the regular 32% w/c and that was it. I say YAY to plants! :-)

Angel079 12-14-2009 12:33 PM

So what you learn from this....leave your fingers off your filter & gravel - If you have a cleaning on your house instead :-)

Glad to hear really nothing major happened!!!

Hawkian 12-14-2009 01:00 PM

Hehe ;-)

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