Fishless cycle stall?

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Polkadots

Aquarium Advice Activist
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Nov 27, 2013
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I think my cycle has stalled!

Today is day 45 of my fishless cycle. The ammonia goes down to .25 every day, so I bump it back up to 4ppm every day. The nitrites remain at 5ppm or up, I can't tell. The nitrates have been staying at 10-20ppm for 18 days! Today I did my first pwc to see if that would get the cycle going. What else can I do to get it going?

Also, the ammonia took a long time to drop: 19 days. The nitrites showed up really quickly... Does that affect anything?

Thanks!
 
Did you happen to check your pH before the water change?
Also, add a pinch of fish flake to the tank. Just a smidge.

Don't dose so much ammonia any more. This is the primary problem and why your cycle will not complete.
Once you see any trace of nitrItes, do a 1/2 dose only every 3-4 days.

Otherwise you will be stuck cycling forever, trying to build more and more and more bacteria. In this time you probably pH crashed and ran out of phosporus, so you've stalled.

Don't dose ammonia again for 4 days, and then only dose it up to 2ppm. Repeat every 4 days and no more often than this. You will find your cycle completes soon.
 
Thank you! I did not check my ph. After reading your reply, I went to check it to find it was still 8.2ish.

But I will follow your advice and won't dose the ammonia so high!
 
As threnjen said, pH could be the problem, but it could also be that your nitrite is WAAYY higher than 5 ppm. I would test pH, and if it is fine do a 50% water change to bring nitrites down. If they are still above 5 ppm, then do more water changes.

Also, only dose 2 ppm of ammonia, every two days. You don't need so much. I'm willing to bet that by now, your nitrite is quite literally around 20-50 ppm. Yes, nitrIte! You've been dosing 4 ppm of ammonia for 18 straight days, so it ought to be at least in that range, if not higher, and I bet that caused the stall.
 
Howdy howdy! I'll just answer this here.

You'll probably have to do two 100% water changes to get the nitrites to read close to 0 (under 1.0ppm is ok)

Then dose the system to 4ppm and check again in 24 hours that it has cleared.
 
Last edited:
Howdy howdy! I'll just answer this here.

You'll probably have to do two 100% water changes to get the nitrates to read close to 0 (under 1.0ppm is ok)

Then dose the system to 4ppm and check again in 24 hours that it has cleared.
You mean nitrites not nitrates, right?
 
Alright, then, I'm going to go ahead and do the water change right now! Thank you!
 
all right, how's it going? WC done? Re-dosed to 4ppm?
if so, let it be til same time tomorrow, then test and report :)
 
I procrastinated- did a 100% water change around 3:00ish. After that, I filled it back up again and tested the water to find that it was around 0 of ammonia, 5ppm or more of nitrites (however the drops were blue before I shook it, rather then the previous purple), and around 20ppm of nitrate. This was the same as before I did the water change. I planned to do 50% water change and see how that goes, but it was almost five and I had dinner plans where I had to leave at five. Therefore, I'm going to do a 50% water change tomorrow and hope it works!
 
I procrastinated- did a 100% water change around 3:00ish. After that, I filled it back up again and tested the water to find that it was around 0 of ammonia, 5ppm or more of nitrites (however the drops were blue before I shook it, rather then the previous purple), and around 20ppm of nitrate. This was the same as before I did the water change. I planned to do 50% water change and see how that goes, but it was almost five and I had dinner plans where I had to leave at five. Therefore, I'm going to do a 50% water change tomorrow and hope it works!

Okay, I realized I didn't allow it the water to circulate or whatever. I tested it again, paying extra close attention this time because last time I didn't really pay attention that much. I found that the nitrites turned from blue to purple- a good sign. Also, I think the nitrates are somewhere between 20-40ppm. The ammonia is at 0. I am going to do the water changes in till the nitrites and nitrates get down to under 1ppm... tomorrow!
 
Finished my 50% water change... I tested the water to find that it was .50ppm nitrites, and 20ppm nitrates. Is this fine? Can I add the 4ppm of ammonia?
 
That day I put it in ammonia up to 4ppm at 9:30pm. I was not able to check it yesterday. Today I checked it to find that the ammonia was at 4ppm, the nitrite was at 1ppm, and the nitrates was at 20ppm. Considering 4ppm of ammonia was being gobbled up by the bacteria in 1 day or less, I'm a bit worried. Is this normal? Am I doing this right?
 
Did you wash your filter media or something or fail to use dechlorinator at the water change? The bacteria don't live in the water, so the WC couldn't have done anything to the existing filtration (unless you didn't dechlorinate)
 
That's so strange... No, I'm sure I didn't was my filter media and I did dechlorinated... But I did declorinate after I filled my fish tank with water, rather then declorinating it before I put the water into the tank. Ahhh... Did I kill my beneficial bacteria?!?
 
Probably not as long as the filter wasn't running while you were putting in the water before dechlor.
is it still at 4ppm today?
 
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