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Unexpected nitrite spike
Posted: Sat Jun 28, 2025 11:39 pm
by frosty9
Just tested my water and got a nitrite reading of 1.0 ppm out of nowhere. Tank is a 20 gallon with 6 Neon Tetras, 4 Corydoras, and a Betta. Did a 25% water change yesterday, filter is a HOB AquaClear 30. Any ideas what's up?
Re: Unexpected nitrite spike
Posted: Sat Jun 28, 2025 11:52 pm
by bites
That's sketchy. Did you add any new fish or mess with the filter media recently? Even moving stuff around can crash your cycle. Also, what's your ammonia reading? If it's zero, your bacteria might be struggling to convert nitrite.
Re: Unexpected nitrite spike
Posted: Sun Jun 29, 2025 12:30 am
by deepfin
I've had this happen after overfeeding. How much are you feeding? Those Corys can be greedy, and leftover food'll spike nitrites fast. Try cutting back to once a day for a bit.
Re: Unexpected nitrite spike
Posted: Sun Jun 29, 2025 1:10 am
by knight
bites wrote: ↑Sat Jun 28, 2025 11:52 pm
That's sketchy. Did you add any new fish or mess with the filter media recently? Even moving stuff around can crash your cycle. Also, what's your ammonia reading? If it's zero, your bacteria might be struggling to convert nitrite.
Yep, second this. Check ammonia first. If it's high too, your cycle's fully crashed. If not, just a partial hiccup. Either way, daily small water changes till it's stable.
Re: Unexpected nitrite spike
Posted: Sun Jun 29, 2025 1:40 am
by thinfin
Gonna throw in that substrate vacuuming might help. Corys stir up gunk, and if you've got detritus buried, it'll leach nitrites. Also, what's your pH? Lower pH slows nitrite conversion, so that could be part of it.
Re: Unexpected nitrite spike
Posted: Sun Jun 29, 2025 2:37 am
by frosty9
Ammonia's at 0, pH is 7.2. Didn't touch the filter, but I did add a new piece of driftwood last week. Could that be the culprit?
Re: Unexpected nitrite spike
Posted: Sun Jun 29, 2025 3:26 am
by bites
Driftwood can sometimes cause a mini-cycle if it's leaching organics. Not usually enough to spike nitrites this high, though. You dosing with Prime or similar? It'll detoxify nitrites temporarily while you figure it out.
Re: Unexpected nitrite spike
Posted: Sun Jun 29, 2025 4:16 am
by chloe
I'd test your tap water too. Sometimes municipalities change treatments, and you get surprises. Happened to me once with chloramine.
Re: Unexpected nitrite spike
Posted: Sun Jun 29, 2025 5:07 am
by deepfin
frosty9 wrote: ↑Sun Jun 29, 2025 2:37 am
Ammonia's at 0, pH is 7.2. Didn't touch the filter, but I did add a new piece of driftwood last week. Could that be the culprit?
Maybe if it wasn't pre-soaked. Rotting wood can suck up oxygen and mess with bacteria. But like bites said, Prime's your friend here.
Re: Unexpected nitrite spike
Posted: Sun Jun 29, 2025 5:28 am
by knight
If you're using tap, check for nitrites there. Some wells have 'em. Also, how old are your test kits? Expired reagents give false readings.