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Mystery Nitrite at Cycle Start


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Hi all, I'm cycling a new 9 gallon nano tank. My nitrite readings have been high ever since I started the cycle. I added ammonia on Day 1 (Dr. Tim's, 4 drops per gallon as recommended on the bottle). Day 2 I tested for ammonia and nitrite. Both were higher than I expected. Ammonia was around 4ppm and Nitrite was (I thought) around 2ppm. 

Two days later ammonia had dropped to 0 and nitrite was still at 2ppm. 

In retrospect, I think I misread the API test for the nitrite from the start. The colors for 2ppm and 5ppm are virtually indistinguishable. I assumed 2 because I couldn't figure out why the nitrite levels would be so high. It's so early in the cycle I didn't expect nitrite at all.

But, now I'm about a week into the cycle, I've done three 50% water changes over the lsst 3 days and nitrite is still hanging in that same high range. 

Today I tested with my strip test from Aquarium Co-op and it looks like nitrite is at 10ppm or higher. I haven't added ammonia in days and did a 50% water change before getting that 10ppm result. Ammonia continues to read 0ppm.

I just can't figure out where the nitrite is coming from!

In case this info helps...

I used inert black sand substrate, petrified wood, and a small piece of driftwood (reused from another tank, boiled and scrubbed to remove any algae from the previous tank). I planted a bunch of anubias, buce, and Java Fern (used the Reverse Respiration technique recommended on this forum to clean the plants first). I added a dose of Fritzyme 7 and then left the plants to rest with no light for a week before starting the cycle. 

The plants are doing great. No livestock. Just buttloads of nitrite...

Any ideas why this is happening or what my next steps should be?

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Have you tested you tap water? The amount of nitrite you get is linear 1ppm ammonia will be 2.7 nitrite and 3.6 nitrate anything else is coming from somewhere else or a false positive 

you could also put a drop or two of your ammonia in a 5 gallon bucket with water and see if it has nitrites in it 

also might be worth it to test water that’s been in any buckets or containers your using I had a bucket that was leaching large amount of ammonia

Edited by face
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Great question, face. I haven't tested tap water because I'm also running a QT tank and an established tank that are not showing these high nitrite levels. Maybe I'll check anyway.

I'm wondering now if the Fritzyme 7 could have been DOA. If I (unknowingly) poured a bunch of dead bacteria into my tank a week prior to starting the cycle, I wonder if that could produce enough ammonia to lead to these high nitrite levels?

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Maybe at tap water, the Dr. Tim's, and the Fritzzyme (if you still have some) to a bucket and see what it measures?

If there was anything else you added to the tank (like fertilizer) throw some of that in the bucket too...

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The bacteria that eats nitrite grows slower than the bacteria that consumes ammonia. Also if you have plants, they can also consume the ammonia direct which could make things look weird.  Honestly if you are showing 0 ammonia and high nitrites, you're half way there. Eventually you'll see the nitrites be replaced by nitrates, and then give it a week where it's repeated and then you should be good.

Honestly having just done a fishless cycle, I'm not impressed.  I think plants followed by a hardy fish with limited feeding, and water changes as needed the first month is more practical. I know I had to  dose my bacteria (Fritz Zyme 7 from Co-op) several times during the process, which was only practical because it was a 10 gallon tank. Better yet, find someone with a sponge you can steal from them, or plan ahead and give them one to seed for you.  It took just over 3 weeks (which to be fair is pretty quick), which was fine because I wasn't in a rush. But I can see it getting frustrating if you watch youtubers fill a tank and just dropping a 100 fish and a bottle and calling it good.    

Bottom line you're going from near sterile to a bacteria farm, and it's going to take time, and that bacteria needs to be treated like a pet and fed to grow up.  So in the future i will just let  1 or 2 hardy fish and their food feed it along with new plant decay and algae growth.  Also plan ahead and buy my sponge earlier so It can go in my main tank before my new tank.

Also does anyone else feel it just seems wrong dropping Ammonia in a fish tank? Seems counter to everything we try to do.

Edited by Lonkley
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Hey Galabar and face,

I ran some tests as you guys suggested. Here's what I found...

Test 1 - Tap water and Prime = 0 nitrite and 0 ammonia

Test 2 - Tap water,  Prime, and Fritzzyme 7 = 0 nitrite and 0.5ppm ammonia

Test 3 - Tap water,  Prime,  Fritzzyme 7, and Dr. Tim's Ammonium Chloride = 0 nitrite and 4ppm ammonia.

Seems like the Fritzzyme is dead and producing ammonia. The Dr. Tim's may also be more potent than labeled. 

(I started with 1 gal water and dosed each add-in accordingly.)

So, I think I dumped a ton of ammonia into my tank when I added the dying Fritzzyme. That must have caused the initial spike. I guess I've been fighting that ever since. Adding the Dr. Tim's ammonium chloride just exacerbated it.

And, as Lonkley pointed out,  the nitrite-eating bacteria grow more slowly. So, here I am. 

I guess the good news is I have a head-start on the ammonia-eating bacteria. ;)

Gonna do another massive water change and see where that gets me.. 

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