If you are doing a fishless cycle or giving advice to others...please read this:

[eco23]

To put this simply...you do NOT need to do water changes every time your nitrItes are high during a fishless cycle.

For some reason this advice is being passed around the site, but it is simply not true.

High nitrItes are an expected phase of cycling a tank. This is one of the reasons people choose to do fishless cycles, so you don't have to stress about your fish or constantly changing water every time it spikes.

There is some debate whether sky high nitrItes actually become toxic to the bacteria, but in my opinion it would take ridiculously high levels for that to even become plausible. My belief is that stalls and pH crashes are not normally caused by the nitrIte levels themselves...they are caused by the nitrifying bacteria using up the nutrients and buffers in the water during the process of PRODUCING the nitrItes and nitrAtes. A pwc or two at the height of your cycle will restore those things and also reduce the no2 in the process.

Pwc's wont hurt. I personally recommend doing 1 or 2 during the process to restore the nutrients and alkalinity that will prevent the crashes and stalls. If you'd like you can even do a massive one (90%) to really get the number down. But again, not every couple days like is recently being advised.

Now, if you're past due for completing your cycle and you want to try a little trick, you can get the no2 down to .5-1 with a large pwc, and then only dose the ammonia to ~1ppm for 3-4 days. That will slow the nitrIte production and potentially give the no2 > no3 bacteria a chance to catch up. This normally isn't necessary, but if you feel things aren't finishing when they should...it won't hurt to try.

If you enjoy doing water changes every day or two...there really isn't a need to be doing a fishless cycle, you might as well have fish in the aquarium because the constant pwc's would be keeping the toxins down anyway. We WANT toxins in the tank during a fishless cycle.

Thanks

[mfdrookie516]

Some scientific proof would be lovely. High nitrites and stalled cycles go hand in hand 90% (just my purely opinionated intelligent observation). Otherwise, its all opinion.

[eco23]

Originally Posted by mfdrookie516

Some scientific proof would be lovely. High nitrites and stalled cycles go hand in hand 90% (just my purely opinionated intelligent observation). Otherwise, its all opinion.

You're right, it is my opinion to a degree...but I think it's been shown over and over again that fishless cycles have been completed without issue with only one or two pwc's to reduce no2...or in many cases no water changes at all. Water changes every 2 days basically goes against the principle of fishless cycling and removes one of the benefits of doing it.

[mfdrookie516]

You didn't say every 2 days in your post. You said "you do NOT need to do water changes every time your nitrItes are high during a fishless cycle"... which I completely disagree with. Had you said every two days, things would be different.

[jetajockey]

Originally Posted by eco23

Water changes every 2 days basically goes against the principle of fishless cycling and removes one of the benefits of doing it.

might as well be fish-in cycling



It's a nice service message Eco but honestly many people tend to give advice without having any tangible experience or even a solid knowledge base on the subject.

So I think the answer (besides these clarification threads) is to address the issue in the threads that they pop up in as well.

[Aspencer]

Originally Posted by mfdrookie516

Some scientific proof would be lovely. High nitrites and stalled cycles go hand in hand 90% (just my purely opinionated intelligent observation). Otherwise, its all opinion.

1+

I have only one experience but it follows what rookie says...My cycling went well until I had NitrItes so high that it took multiple water changes to get it down to readable levels and then when it did get down, the cycle completed itself quickly. Maybe because the bacteria could process what NO2 that was left...sort of like dosing to ammonia to 4 ppm and then the tank can handle fish bioload since as a rule, it is much less than 4 ppm

[eco23]

Originally Posted by mfdrookie516

You didn't say every 2 days in your post. You said "you do NOT need to do water changes every time your nitrItes are high during a fishless cycle"... which I completely disagree with. Had you said every two days, things would be different.

I actually referenced it twice in the post. The reason I bring this up is because there is a trend recently of people doing large pwc's, then the next day nitrIte is high again...and people hop on the threads saying "you need to get nitrItes down", when they had literally done a large pwc the day before.

[jetajockey]

We need some kind of study or writeup about nitrite toxicity towards nitrifying bacteria. I don't even know the exact amount of toxicity of ammonia towards nitrifiers apart from what I've gleaned here and there.

[eco23]

I have a strange feeling people are reading the first line and not reviewing the rest of the post. I clearly state reducing the no2 at different points is something I personally recommend..it is the excessive habit developing of people feeling they need to constantly be doing them that I am addressing.

In fact, one of the reasons I put together the write up in my signature was to include pwc's as part of the process. I researched every article I could find before doing it myself, and barely found any reference to water changes. I did a 50% pwc at the height, and my cycle still completed in 21 days. One of the problems I had was a sharp pH drop on the last day...and that is information I felt would improve the process.

[FishieMomma]

Originally Posted by eco23

....it is the excessive habit developing of people feeling they need to constantly be doing them that I am addressing.

That would be me! lol

I've been wasting water. oops.

[ocean]

Some time ago when I had 10 freshwater tanks I always did a fishless cycle and never did a water change during. I do the same with my SW tanks now, no water changes during the cycle. Same with my two betta tanks. I will admit having liverock is a bonus, short cycle!!!

[-Mac-]

I allowed my nitrites to top 10ppm before ever bothering to do pwc's. After doing steep pwc's three days in a row, only to be well above 5 on the fourth day, I got stubborn about it and just went every other or third day. My cycle marched along nicely despite my refusal to do pwc's every day to keep nitrites readable. My experience suggest that pwc's every 2nd or 3rd days is sufficient (so long as nitrates don't go off the charts too.)

[eco23]

Just to sum up my opinion here since I've been saying it on other threads as well....there is nothing wrong with pwc's during a fishless cycle. There are particular times and situations where they truly are mandatory IMO to reduce no2, prevent stalls, stop pH crashes and also restore nutrients and buffers to the water.

That said, the trend recently of people giving out advice that every single time nitrIte approaches 5 it's time for an immediate water change is unnecessary guidance IMO/E. During the late stages of cycling fishless, no2 can rocket up to 5 within a matter of a day...if people are excited to change water every couple days...I personally advise skipping the fishless cycle, slowly stocking the tank and performing the frequent water changes necessary to keep the toxin levels down. During a fishless cycle...we want toxins. The toxins are what develops the massive bio-filter created during the process.

During a fishless cycle, you shouldn't be afraid of water changes. Feel free to knock down the no2 a few times (pwc's also have the benefits I listed above)...but breaking out the bucket every single time your no2 test tube turns purple simply isn't necessary and removes one of the advantages of cycling without fish.

[TheJT]

I have the tank waiting to start a fishless cycle. I have a liquid test kit that will do NH3/4, NO2, NO3, and Ph. Is there any other measurements that would be needed for a study to be completed?

[eco23]

Originally Posted by TheJT

I have the tank waiting to start a fishless cycle. I have a liquid test kit that will do NH3/4, NO2, NO3, and Ph. Is there any other measurements that would be needed for a study to be completed?

KH can be interesting to know...but it's not necessary. As long as pH is not extremely low there should be no problems...but if you experience wild fluctuations or drops in the pH level...buffering the water may be worth considering, but it is very rarely needed unless you have extremely soft, low alkalinity water. There's some info in the guide in my signature to check out . Good luck!

[eco23]

The main challenge of doing a study of what causes stalls is that there are more variables than simply the nitrIte level. Unless there is a way to clearly monitor the levels of nutrients and buffers, and be able to compare their decline to the rise of no2...I've got to go by experience and first hand accounts in the advice I give.

[TheJT]

Originally Posted by eco23

As long as pH is not extremely low there should be no problems...

Lol my pH is normally 8.0. So let me get a few more things together for the tank and I'll start a new thread and post the test results daily. When the cycle completes or crashes I'll post the findings. Then I can empty the tank, give all the bacteria time to die and repeat the results. I will use 0 seeded material and do the tests at the same time period in 24 hr intervals. I will run a full gambit of tests each time. Hopefully 2 cycles will give us enough data to draw a significant conclusion based at least around my tap water conditions, which I will post also as a measure of the "control". Did I miss anything?

[TheJT]

Originally Posted by eco23

The main challenge of doing a study of what causes stalls is that there are more variables than simply the nitrIte level. Unless there is a way to clearly monitor the levels of nutrients and buffers, and be able to compare their decline to the rise of no2...I've got to go by experience and first hand accounts in the advice I give.

Yes, and I can check with my local water department to see if I can get them to test for those nutrient levels prior to and during the nitrite phase. If nothing else we may be able to show a correlation between high nitrites and crashes or completely the opposite.

[Fishguy2727]

It is true that excessive nitrite can be harmful to nitrifying bacteria and therefore stall the cycle, the same is true of ammonia. This means that if the concentration of either gets too high (I have heard 4-6ppm, but I am not sure that those numbers came from studies) water changes to reduce the concentration need to be performed. Your opinion that it would have to be ridiculously high is your opinion, but scientific studies have put numbers to that (although I don't know them off hand).

[eco23]

Originally Posted by TheJT

Lol my pH is normally 8.0. So let me get a few more things together for the tank and I'll start a new thread and post the test results daily. When the cycle completes or crashes I'll post the findings. Then I can empty the tank, give all the bacteria time to die and repeat the results. I will use 0 seeded material and do the tests at the same time period in 24 hr intervals. I will run a full gambit of tests each time. Hopefully 2 cycles will give us enough data to draw a significant conclusion based at least around my tap water conditions, which I will post also as a measure of the "control". Did I miss anything?

So...one without pwc's and one with? Do you have a planned schedule for how often pwc's will be done? I'm all for seeing it, but again...my personal theory is that it is not ONLY an issue of nitrIte toxicity to the nitrifying bacteria (which I'm sure there is some level)...but it is an issue of the nutrients which are consumed by the bacteria in the process of actually producing it.

If you can find a way to monitor the levels of nutrients and trace elements that are consumed by the BB, and be able to measure their decline during the process...that would be a key aspect of the experiment. Even if there was a way to do so, it will obviously differ for each individual because each water supply will provide different amounts of those things.

Fishless cycling was around for a heck of a long time before I ever got involved with it, and with the considerable amount of research I did on it before ever attempting it or putting together a write up...there were virtually no mentions of water changes during a fishless cycle. The basic concept was add ammonia, wait for it to drop, wait for nitrItes, let them drop and done. Theres obviously countless cycles which are completed without ever touching a bucket.

One of the suggestions was that if a cycle stalls, do a water change to get it moving. Now whether the pwc helps by lowering no2 or restoring the things used up during conversion is debatable (most likely a combination of both IMO). One of the reasons I actually did the write up was to include a few pwc's during the process to prevent pH crashes (like I experienced) and/or stalls.

I love experiments and I'm happy to see the results...my only concern is that without having a lab to measure trace elements, and also using different water sources...I'm not sure if anything conclusive can be shown...I'm all up for seeing it though . I would also recommend using entirely new media, and sanitizing the tank before starting for a second time rather than simply letting the bacteria die. The survivability of Nitrosomonas and Nitrobacter without a food source is also debatable and a different discussion.

There are also a ton of cycling logs currently on the forum right now, including daily updates and readings...so I'm sure that would be a good resource to draw hypothesis to a degree as to how things are effected by pwc's and other aspects like adding fish food as a source of phosphates and other nutrients.