Stalled Fishless Cycle?

[bob9009]

EDIT: Cycling is now complete. It only took 33 days, but it felt like an eternity

Hey guys,
I've been cycling my 425L (110 gal) for about two weeks now. I filled the tank up and treated it with Seachem Prime to remove chlorine and chloramine and dosed it with 5ppm of ammonia. I also added some media from my other tank to seed the new filter (100L wet/dry sump).

The temperature is set to 27 degrees C (80 deg. F)

On the second day, I got a reading for nitrites and they were off the card by the 5th day. Nitrates showed up on the 4th day, rose to about 7.5ppm over the next few days and then just stopped (day 7). They've been at ~7.5ppm for the last 7 days.

The nitrite-producing bacteria seem to be doing ok, and are eating 3-4ppm of ammonia daily. I had to dilute the water sample quite a bit to get a reading, but I think nitrites are at about 50ppm.

Is it possible that my high nitrite environment is actually stopping the nitrate-producing bacteria from colonizing?

 

[waterdrop]

I doubt it. Your nitrite environment doesn't seem out of line with what we see in typical fishless/clone situations. Sometimes its more difficult to clone the nitrate producers over than it is the nitrite producers, so you probably just need more time. Ideal temp and pH would be 84F and 8 to 8.4 pH, although I wouldn't try to alter the pH, that's just to know to understand another factor that might effect the quickness. Bacteria growth rate slowly drops off as the pH gets lower, stalling at 6.2 and pretty much stopping the fishless process at about 6.0.

~~waterdrop~~

 

[bob9009]

Thanks for the reply mate

My pH did crash to 6.2 a few days ago, but I brought it back up with sodium bicarbonate. Now it's hovering in the range of 7.2 to 8. It comes up to around 8 after I add ammonia but then drops back off to about 7.2.

It's good to hear that my situation isn't abnormal. I was really worried about the nitrates flatlining at 7.5 after coming up so early. I'll just keep feeding the nitrite-producers and keep my fingers crossed that their buddies show up soon!

 

[waterdrop]

When nitrate(NO3) begins to pass the 160ppm range, it becomes more likely that the small percentage of ionic state that hovers in the water as nitric acid will, in addition to having a lowering effect on the pH, also have a suppression effect on N-Bac growth, possibly. 7.5ppm is obviously nowhere near 160ppm.

~~waterdrop~~

 

[bob9009]

Right now, I'd welcome nitrate at 160ppm - at least it would be progress!!!

I know it's not really diagnostically important (since I've already been diagnosed as impatient), but here's a graph of my parameters anyway:

Nitrite has flatlined becuase it's off the card.

 

[waterdrop]

Your graph shows a very typical fishless cycle. Further confirmation that you're doing fine.

You are probably putting too much stock in getting real feedback from your nitrate(NO3) readings. Its fun when first learning about the nitrogen cycle to picture the progress and measurement of the nitrogen in the various compounds and to assume you will be able to see them in a steady and clear progression. Unfortunately reality seldom works out that way. The low-cost everyman-doable liquid nitrate test is a very flakey thing. Even with the minimal shaking times recommended within the API nitrate test for instance, the amount of shaking and the quality of results are minimal. Any analytical dye chemist would probably tell you not to expect a lot from these tests. There's a further issue that high amounts of nitrite(NO2) will throw the test off and I believe that might vary a bit with pH too! So using the nitrate(NO3) test to confirm what's going on with the end product of the cycling is not a very reliable thing unless you just look at the long trend on a graph such as you have presented and disregard the day to day fluctuations.

Another reason nitrate(NO3) is a core test that's included in the typical freshwater master test kit is for the entirely different purpose of checking your tank maintenance results month after month later on after cycling has long been forgotten. Nitrate(NO3) levels serve as an excellent objective feedback tidbit to warn you if your weekly gravel-clean-water-changes have slipped to being too small for your given fish and plant load. Nitrate is used like a "canary in the coal mine" to not only warn you that nitrate itself is getting a bit high but also as a surrogate for the hundreds of other heavy metal, inorganic and organic substances that we can't afford or don't have time to measure in the tank but which we don't at all want to have invisibly building up!

~~waterdrop~~

 

[bob9009]

Thanks for the detailed reply waterdrop!! It's great that someone as knowledgeable as yourself takes the time to explain this stuff to beginners like me.

I'll try to relax now and just let the tank cycle

Thanks again!

 

[bob9009]

After reading some other threads, I think I might've found an error in my method. I've just been trying to maintain 3ppm of ammonia by adding ammonia whenever the tank was down to 1ppm or less, even if it dropped to 1ppm several times in a day. From what I've read, it seems that the nitrite oxidizing bacteria aren't big fans of ammonia.

I've cut back to dosing ammonia once a day, and added some squeezings from the filter in my cycled tank. Hopefully that helps things along.

 

[waterdrop]

In my opinion, the ideal approach to adding ammonia in the the Add&Wait method is to wait until the -day- when ammonia tests all the way down at zero ppm. Regardless of what time of day it tests at zero ppm, one then waits until the usual hour of the day that one has set for adding ammonia and adds it then. The point is consistency in ones habits, which can be a help if one forgets to log or something. Ammonia is never added more than once a day and only on a day when ammonia reached zero sometime in the previous 24 hours. Its no problem to the bacteria to be without ammonia the better part of a 24 hour period and in fact, not overloading the process input ammonia is better in the long run. The N-Bacs (nitrite oxidizing bacteria) actually are supposed to display reduced growth mostly if the nitrate(NO3) gets really high (perhaps 160ppm and up or so.) I don't think I've seen comments on them showing reduced growth rate due to very high nitrite or ammonia levels, although that's possible. We don't want ammonia to get up near 8ppm because it promotes growth of a different and incorrect species of ammonia oxidizing bacteria, which will ultimately be bad for the overall process.

~~waterdrop~~

 

[bob9009]

Thanks for another very informative reply mate

I've never dosed the tank to a level higher than 5ppm, so hopefully I haven't established a colony of the bad ammonia oxidizing bacteria.

 

[OldMan47]

The wrong AOB won't really hurt anything but would not be moving your cycle forward either. That is why the caution about high levels.

 

[bob9009]

That's good to know. Thanks bud

 

[bob9009]

The waiting is killing me!!

I did another nitrite test tonight by diluting a tank sample to 1/100th strength. The result was about 100ppm, which I think is reasonably accurate given that I've added about 43ppm of ammonia to the tank. The ammonia should have been converted to somewhere around 86 - 108ppm of nitrite so 100ppm seems like it's right on the money, even if the result is somewhat discouraging (I was hoping for something a little lower).

I know I shouldn't put too much stock in a test performed with an off-the-shelf test kit, using a diluted sample with the results displayed as a colour, but it's hard not to. Everthing significant in the process so far happened in the first few days.

Maybe I need another hobby to distract me from this one

 

[waterdrop]

Yes, its a little like trying to watch hair grow (except with that I guess you could measure the length, lol, picture a whole forum of people reporting how far along their strand of hair is...)

Your graph makes it look like you must have gone at least about 15 days. If you're very lucky it might only take another 20 days or so or if you're a little less lucky, but not that far off from average, you might be about 1/4th the way through, but of course the whole point of us yakking about it all the time is that its quite unpredictable overall.

Your other hobby could be going off to the species forums and trying to draw tips out of experienced fishkeepers about the particular species that you are building into your stocking plan. You could also explore plants (which are harder than fish in my opinion) and see what can be learned over there, or you could read old threads about processes or hardware that you're interested in. There's nearly always other stuff to be learned.

~~waterdrop~~

 

[OldMan47]

Lets not go to hair WD, I can't seem to grow any these days. At 15 days, the cycle is at a point where some people are just starting to see their first ever slight movement of ammonia and have no idea what a nitrite spike look like so you are way ahead of those folks. I know it is hard to be patient at this point but it is really about all you can do. Another thing you could spend some time doing is looking through the fish selections at the LFS and trying to decide what you might like to put into your cycled tank. Then you could come back and discuss how to stock and which combinations work or don't work. It might take your mind off the empty tank for a few seconds anyway.