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Discussion Starter · #1 ·
I'm cycling a bare 29g tank and my nitrites seem to be stuck around 2.0 ppm. They have been there for over 2 weeks and my other tanks all had their nitrite spike and fall in about a week. My ph is 6.8-7.0 Ammonia showing 0.25 ppm and my nitrates are at least 40 ppm (Salifert test only goes up to 40 ppm). I can't decide whether to do a partial water change now or wait a bit longer to see if the nitrites drop. Suggestions?
 

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I'm cycling a bare 29g tank and my nitrites seem to be stuck around 2.0 ppm. They have been there for over 2 weeks and my other tanks all had their nitrite spike and fall in about a week. My ph is 6.8-7.0 Ammonia showing 0.25 ppm and my nitrates are at least 40 ppm (Salifert test only goes up to 40 ppm). I can't decide whether to do a partial water change now or wait a bit longer to see if the nitrites drop. Suggestions?
When you say this is a bare tank I am assuming you mean no plants, no substrate, no hardscape?

Anyway there is no reason not to do a water change. If you need to redose ammonia when its done (or add fish food if that's how you are doing it) then just do so.

Cycling is weird, it takes however long its going to take. I've seen tanks cycle in a week, and others take 5 or 6 weeks. I usually don't bother doing much in the way of water tests till a month has gone by.
 

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Hi @butchblack

In order to best advise you, the following information is important:

[1] Did you use a bottled bacterial starter such as Dr Tim's or Tetra SafeStart?

[2] What is your tank temperature?

[3] What was your starting ammonia level?

[4] What type of filtration are you using?

[5] Are you using tap water? And, did you use a tap water conditioner?

I'll leave it at that for the moment - other than to say that it's not uncommon for tank 'cycling' to get stuck at the nitrite stage and there are good reasons why this can happen.

Anon
 
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Discussion Starter · #4 ·
Hi @butchblack

In order to best advise you, the following information is important:

[1] Did you use a bottled bacterial starter such as Dr Tim's or Tetra SafeStart?

[2] What is your tank temperature?

[3] What was your starting ammonia level?

[4] What type of filtration are you using?

[5] Are you using tap water? And, did you use a tap water conditioner?

I'll leave it at that for the moment - other than to say that it's not uncommon for tank 'cycling' to get stuck at the nitrite stage and there are good reasons why this can happen.

Anon
1. I'm using Dr. Tims
2. 82°F
3. 3.0 ppm
4. a large sponge filter and a Fulval U2
5. Tap water with Aqueon water conditioner ph adjusted to 7.2-7.4
 

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Hi @butchblack

Thanks for the data. As the nitrifying bacteria need both carbon and phosphorus to reproduce, I'm wondering if your tank has been depleted of these critical nutrients. Carbon can be provided by dissolved atmospheric CO2 but, in my experience, it soon gets used up. I usually keep a close watch on KH, which is often provided by carbonates and bicarbonates. Please measure the tank KH - it should not fall below 4dKH*. And, I have always tried to ensure that phosphate remains at around 0.06 mg/litre. If you don't have phosphorus as a plant fertilizer and it's been depleted from whatever was in your tap water, I suggest making a paste with a few flakes of fish food and tank water, then adding it back to the tank. Obviously, the tank water will get cloudy but this can be dealt with later. You could also try raising pH a little higher - something like 7.6 to 7.8.

I hope this is of some help.

* Please note that I'm in the UK where we adopt German degrees for water hardness. But, I use the API test kit for KH and GH for which I've never had any need to do any conversions.

Good luck!

Anon
 
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