# Water change causing Nitrite spike?



## ccla (Feb 2, 2009)

I have been having trouble lowering the Nitrites in my cycling tank (see here). For the last 4 days Nitrites in the tank have been zero.
I was planning to order the fishes on Monday to be delivered this coming Friday, so in preparation I did a massive water change this afternoon (about 50%-60%) since my Nitrates were so high (after the water change, Nitrates are still above 80).
I checked Nitrites right before the water change and they were at zero. I do not know why but I tested them again after the water change and they were at 1. What could cause this?
I performed the water change on three separate tanks, and all of the other tanks still read at zero as well as the tap water.
I am really at my wits end as to what could have happened. Any ideas?


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## ladybugzcrunch (Jul 26, 2009)

2 things. Test your tap water, it may have nitrites in it, or did you vaccume the gravel, clean the filter? Perhaps there was just enough bacteria to keep it going. I once vaccumed and rinsed the filter media on the same day and had a nitrite spike in a tank that had been cycled for months. The spike only lasted a day or so though. Test your tap water and then test your tank tomorrow and see whats up in there.


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## ccla (Feb 2, 2009)

Tap water has no Nitrites in it (tested it once I found the Nitrites in the tank). By the way I am using the API Master Kit.
I did do a pretty heavy vacuuming of the Argonite substrate, but why would that create a Nitrite spike?


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## Maxima308 (Jun 6, 2009)

Could it be a false reading caused by your water conditioner? Weird you haven't noticed it in the "other" tanks. Perhaps the tank was never fully cycled and the heavy vacuuming disrupted the cycle....


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## prov356 (Sep 20, 2006)

I've seen massive water changes on newly cycled tanks cause nitrite spikes. I frequently warn folks here about that. I've seen it more than once and others (now you too) have reported the same. Fortunately the spike only lasts for a day or two. Better to do a series of smaller changes, rather than one or two massive ones.

If fish are on the way and you have to choose between massive water changes or elevated nitrates, go with the elevated nitrates. They won't outright kill your new arrivals, and you can continue the small water changes to get them under control. Best of course to get nitrates under control before fish arrive.

Why this would happen I can only guess. Obviously the bacteria that convert nitrite are a bit fragile in the early going, more so than the ammonia converters. Maybe because the thin, hard biofilm that they inhabit hasn't had time to build, so it leaves them exposed and vulnerable. Maybe both the ammonia and nitrite converters are lost in equal numbers, but the ammonia converters bounce back more quickly. So much so, that we don't see a measurable ammonia spike. Seems logical since it takes the nitrite converters 2-3 times as long to get established in the first place. Or maybe I'm totally wrong and it's something else entirely. 

Just leave things alone for a day or two and let the nitrite drop. Then resume with 25-30% changes, no more.


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## ccla (Feb 2, 2009)

Maxima308 said:


> Could it be a false reading caused by your water conditioner? Weird you haven't noticed it in the "other" tanks. Perhaps the tank was never fully cycled and the heavy vacuuming disrupted the cycle....


I do not know, I use Prime and it never gave me false Nitrite positives before. Maybe the vacuuming disrupted the cycle (which must be in its 6th or 7th week by now) but why would it? And so suddently? The Nitrite reading was done about 1 hour after the water change. How could Nitrite spike in such a short time?


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## smilepak (Aug 9, 2004)

Why would vacuum cause a spike?


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