Is this really possible? (Fishless cycle question)

[aidenagreen]

Hey all, I'm not new to keeping fish but I am starting my first tank in almost 10 years. I've never done a fishless cycle before so I thought I'd try that out. I've been cycling my 40g tank for about 3 weeks now using pure ammonia and I've been testing daily since my ammonia started dropping but it's been a slow process (4-5 days between dosing and when it would hit 0). Today it's been about 3 days since my last test and ammonia addition. 0ppm ammonia for the first time, nitrite and nitrate, they both turned dark purple and dark red (respectively) immediately after I shook them. So after work today I did a 50-60% water change, added ammonia, and let it wait. When I checked, the nitrite and nitrate both turned dark purple and dark red again but not quite as quickly this time, it took about 4 minutes to get to full color. My main question after this wall of text is pretty simple: is it really possible for that much ammonia and nitrate to still be left over after that much of a water change?

 

[plantnoob]

Yup, possible. I'd do another water change to get nitrites down and not add any ammonia until the nitrite levels go down to zero. Otherwise your cycle will stall.


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[Fresh2o]

I think you mean nitrite and nitrate, and yes, they can still be elevated after a large water change. You may need to perform additional water changes to bring them down.
First off, what brand of test kit are you using? If it is API, then you need to read the test after the required amount of reaction time. The fact that an intense color change occurred immediately (pre-water change) suggests that the levels were well beyond the test ranges (very high). In that case, for testing purposes, you can dilute the tank water with distilled water and retest. For instance, take one part tap water, three parts distilled water, mix, test, and multiply the result by four.
OR...do water changes to bring the levels down.
How much ammonia were you dosing and what target level were you aiming for (4 ppm, 2 ppm, etc)? Generally it is 4 ppm but I usually shoot for 2 ppm (person preference).


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[aidenagreen]

It is the API kit and I did read it after the 5 minutes, I just wanted to point out that it didn't even take that long to get all the way up to the max reading. My target ammonia level is about 4ppm. And will my cycle really stall if I keep adding ammonia like plantnoob said? Wouldn't I be starving the ammonia-eating bacteria?

 

[Fresh2o]

Thanks for the clarification of brand and I understand about the timing part.
Supposedly (sorry, no link to substantiate this), elevated nitrite leads to a stalled cycle. I've heard it from multiple sources. The only thing I can think of is that the nitrite level is so high that the developing bacteria cannot keep up with it. Therefore, it appears to have stalled.
I prefer using 2 ppm as a target for ammonia. Reason: I don't plan on heavily stocking right after the cycle has completed.
No, skipping a few days should not affect the bacteria.


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[aidenagreen]

I've got an update in case you're curious. I've done a few PWCs in the following days and the nitrite level still didn't go down very much so I just did A HUGE water change (80%-90%) because at this point I'm just amazed at the readings I'm getting. Doing a test as I type this.
Waiting
Waiting
Waiting
Waiting
Waiting
Well I actually got to see that pretty sky blue when I put the tester in for the first time this week but after 5 minutes I've still got a dark purple, reading right at the end of what the test shows. I'm not really sure what's going on but I'll see what happens over the next few days.

 

[NickNaylor]

Agree with the above that this is certainly possible.

I'm currently in the process of cycling my first tank (a 30-gallon) using a fishless cycle. I accidentally added WAY too much ammonia to get the process started. My readings were like yours: immediately turned the highest possible reading. With time (and despite this insanely high ammonia level), the colors would gradually change more slowly though they will still have the maximal reading. After several days, my ammonia eventually went down to zero and has remained zero when testing despite adding ammonia to the tank daily. It took about two weeks to get to this point.

I'm now having a similar experience with nitrites: as soon as the reagent is added, it would turn a dark purple at the bottom of the test tube before I even mixed the water and reagent. That was about a week ago. Now the changes are more gradual but, again, I'm still getting the highest possible readings at the end of the test about a week after the nitrites first become positive and spiked.

I'm not sure that I believe the high ammonia/nitrites resulting in a stalled cycle (unless they're so high that they become toxic to the bacteria), but if you give everything a little time and you aren't getting anywhere, I think it's reasonable to do water changes to lower your levels to within a measurable range.

Good luck.

 

[shevek]

I'm also experiencing a similar situation. I'm on Day 18 of a fishless cycle, and 4ppm of Ammo goes to 0 within 24hrs. But nitrites are stuck at deep purple for about 8 days and nitrates have stayed at 5ppm over the same period. I was expecting nitrates to rise off the charts by now. I tried a 50% water change yesterday, but didn't see a difference in today's results. I guess more water changes are needed?

 

[NickNaylor]

I'm also experiencing a similar situation. I'm on Day 18 of a fishless cycle, and 4ppm of Ammo goes to 0 within 24hrs. But nitrites are stuck at deep purple for about 8 days and nitrates have stayed at 5ppm over the same period. I was expecting nitrates to rise off the charts by now. I tried a 50% water change yesterday, but didn't see a difference in today's results. I guess more water changes are needed?

It will take time for the bacterial colonies to develop. Most people say that it takes longer for the nitrite -> nitrate population to develop than the ammonia -> nitrite population, and that was certainly the case in my cycle.

Doing water changes to try and get your nitrites to a measurable level isn't unreasonable, but I otherwise wouldn't be in much distress over the fact that you haven't gotten much activity at this point.

 

[shevek]

It will take time for the bacterial colonies to develop. Most people say that it takes longer for the nitrite -> nitrate population to develop than the ammonia -> nitrite population, and that was certainly the case in my cycle.

Doing water changes to try and get your nitrites to a measurable level isn't unreasonable, but I otherwise wouldn't be in much distress over the fact that you haven't gotten much activity at this point.

Starting to finally make progress. I did 2 additional 40% water changes, and nitrites came down a little bit. Still 5ppm, but not immediately purple when I start the test. Also, I have only been dosing ammonia to 1ppm over the same period. Finally, my nitrates started rising are were 80ppm yesterday. I was definitely overdosing ammonia, generating way too many nitrites.

 

[NickNaylor]

Starting to finally make progress. I did 2 additional 40% water changes, and nitrites came down a little bit. Still 5ppm, but not immediately purple when I start the test. Also, I have only been dosing ammonia to 1ppm over the same period. Finally, my nitrates started rising are were 80ppm yesterday. I was definitely overdosing ammonia, generating way too many nitrites.

Good work. Just stay patient - I promise it'll start working. Just gotta let nature do its thing.

I think continuing to do water changes until your nitrites are readable isn't a bad idea. Additionally, the water changes will help keep your nitrates reasonable, which will make it easier for you to add fish once you're at that point. I neglected my nitrate levels when I was cycling, and as a result I had to do multiple, large volume water changes for a few days before my tank was ready for critters.