trouble with fishless cycle

[pckroeger]

Hi all, thanks very much for the help.
I am still very confused. I am aware I overdosed initially, but it has been 2 and a half days and my ammonia has stayed at 0.25ppm. It drops from 3ppm to 0.25ppm in one day, but it has stayed at 0.25 for almost three days. So there is bacteria there to drop 2.75ppm in one day, why isnt that bacteria dropping off the last 0.25ppm in three times the duration of exposure??? I have got test results of 0ppm with this test kit before so it cant be showing 0ppm as 25ppm.
I am so confused :( i thought i was getting somewhere with my cycle but it seems to have stalled or something!

[imma24]

Hmmm - are you sure it's .25? What test kit are you using just out of curiosity? Forgive me if you've already posted this but have you gotten a reading for nitrItes yet?

[pckroeger]

Hmmm - are you sure it's .25? What test kit are you using just out of curiosity? Forgive me if you've already posted this but have you gotten a reading for nitrItes yet?

I use an API liquid master freshwater test kit, and when I started cycling I got readings of 0 so it should be showing the right reading now. A couple if weeks ago I saw a nitrite spike and have been dosing half the initial ammonia I did since then. Initially the ammonia was dropping to 0 after a couple days but since then it has only been dropping to 0.25 and staying there :(

[fishmommie]

I use an API liquid master freshwater test kit, and when I started cycling I got readings of 0 so it should be showing the right reading now. A couple if weeks ago I saw a nitrite spike and have been dosing half the initial ammonia I did since then. Initially the ammonia was dropping to 0 after a couple days but since then it has only been dropping to 0.25 and staying there :(

Sorry you're still having trouble. What are your nitrites and nitrates reading? And are you still dosing ammonia? If it's never dropped down to 0 again, then don't dose until it does. just wait it out. this is not going to happen in just a couple of days. it's going to take some time. THEN when ammonia drops to 0, only dose back to 1 and see what happens.

[myofibroblast]

This is interesting. I'm a beginner and I haven't used the fishless cycling method myself, but have often wondered about the biology of the method. I suspect people will not be able to answer the question of why your ammonia level continues to stay at 0.25ppm despite initial success, without knowing all the details (even still).

You provided clear evidence that ammonia oxidation is present (3ppm -> 0.25ppm), but the question is why it's hovering around 0.25ppm without further oxidation. Not thinking about this deeply, three quick possibilities come to mind:

1. test kit (colorimetric kits are not meant to be precise, but give us a general sense of the range) - I use the API kit as well, and it doesn't seem like that is the issue for you as you were able to get zero ammonia level before.

2. exogenous ammonia. Sounds like you've tested the tap water and there isn't any additional ammonia. I'm assuming there aren't decaying debris in the aquarium, since you mentioned you're adding ammonia.

3. suboptimal nitrification. I think this is the most intriguing possibility with many hypotheses for its cause, none of which I think is ultimately important so far as changing your management of the issue, which is to wait for the ammonia oxidizing bacteria to work. When you artificially enrich the nitrogen source (i.e. adding gobs of ammonia to an aquarium), you're likely selecting for the fastest growers in a heterogeneous population of nitrifying bacteria. One hypothesis is that the fastest growers under high ammonia conditions are not the most efficient ammonia oxidizers, and you've selected for them by providing high ammonia levels used in a fishless cycle. Once the ammonia level drops to 0.25ppm or lower, maybe they are just not that efficient, and you need to wait for the more efficient colonies to out-compete the overpopulated, low efficiency bacteria. Another hypothesis is that while you have efficient bacteria, the high ammonia levels have led to a high bacterial load. When the population density increases, bacteria can undergo changes in cellular processes whereby their metabolic profiles (including ammonia oxidation) change to accommodate low nutrient states or impending starvation. If the nitrogen source is abundant (i.e. you giving them ammonia to 3ppm), they may be crowded but they are still happy to metabolize the abundance of food. But once they sense the ammonia level is dropping to 0.25ppm, and they know there are other bacteria packed closely around them, they will undergo changes that limit ammonia oxidation. These are rather simplistic hypotheses, of course, but these came to my mind when I thought about your situation (not very deeply).

As far as management of the situation, tincture of time may be your best friend. If you come up with other solutions, please share! Love to learn more about this process.

[pckroeger]

Myofibroblast you sound like you're the one to go to for fishless cycling help! That explanation was perfect, thanks so much. The third point about suboptimal nitrification sounds spot on. It matches my observations and matches the suggestions of other users on this forum and makes perfect sense, thanks! Also a thanks to all other users for the help :)
I will just wait it out until I get 0 ammonia and dose a smaller amount. When this happens I will repost here.
Thanks again everyone for the stress relief! Can't wait to get cycled and start stocking!

[pckroeger]

Sorry you're still having trouble. What are your nitrites and nitrates reading? And are you still dosing ammonia? If it's never dropped down to 0 again, then don't dose until it does. just wait it out. this is not going to happen in just a couple of days. it's going to take some time. THEN when ammonia drops to 0, only dose back to 1 and see what happens.

My nitrites are 5ppm and nitrates 5ppm but constant, have been 5ppm for a while now. I have stopped dosing ammonia, I will follow your advice and wait till its zero and then dose to 1.
Thanks fishmommie!

[myofibroblast]

pckroeger,

Hope your cycling goes well! 5ppm of nitrites may or may not be enough to inhibit ammonia oxidation. That would be another alternative hypothesis to the suboptimal nitrification. It's an ecological "back-up" in a factory line, if you will. Feedback inhibition is a very common motif in biology, if I remember correctly. Once your nitrite oxidizers start to oxidize the nitrites completely, you might very well see your ammonia levels drop. Google or pubmed/medline this, and you might see some interesting results. On the one hand, high nitrite levels seem to inhibit ammonia oxidation, but on the other hand, ammonia-starved nitrosomonas are resistent to the effects of nitritie inhibition. These make a lot of teleological sense, in a simplistic view, but these experiments were not carried out in more complex environmental conditions where the presence of nitrite oxidating bacteria are also in the mix. Bacteria talk to each other, and so much more is happening than the mere ammonia, nitrite, and nitrates that we test for (because that's all that really matters for the purposes of cycling a tank), and to explain the suboptimal nitrification you're experiencing (hopefully short-lived) one may not have an adequate explanation without more dedicated and involved experimentation. It's fun to think about anyway, don't you think?

[Sandz]

On topic: Just wanted to chime in and say when doing a fishless cycle you want to create a starter culture of bacteria that convert toxic ammonia to a less harful nitrate. You start with 2ppm of ammonia and over the course of a few weeks increase to the tank being able to handle 2ppm per day. It sounds like you havnt let the process complete the first time so its growing at a staggered rate. Let all ammonia dicipate prior to adding anything else and sit and wait. It takes longer in some cases but have patience

off topic: myofibroblast what is your background in? You speak of hypothesis and give potential explanations to an issue but state you are a newcomer to the hobby. Is there any advice you can offer in real life experience? You give some good explanations and show understanding of the tank biology so this isnt a critique but wanted to welcome you to the AC and find out a bit more about you.

[myofibroblast]

Sandz,

I think both experienced and beginners (i.e. me) are in agreement that the best course of action is to allow time for the ammonia-oxidizing and nitrite-oxidizing population to equilibrate without additional nitrogenous source. I am, however, still curious about the high-nitrogen cycling methods and the effects on short-term bacterial stability with high-nitrogen selection and expansion of nitrifying bacteria.

My experience with tanks...hmm, too little to consider. I did keep a couple of small tropical tanks with success in high school, though it was with sadness that I had to give them away when I left home for school. The internet was not existent then (well, I think there was dial-up AOL, but no one could use the phone if you're connected), so a lot of information I gathered was spent asking fish store owners and reading books. Back then, the bacteria were simply referred to as "aerobic bacteria" in many fish store books and by the fish store staff, without specific identification of species or metabolic process. Now after a hiatus from fish keeping, I'm back and very gladly surprised to find so much useful information on the internet! I'm definitely new (again) and curious to read about other people's experience.

As for hypothesis generating, it's just a habit of living, in general, no? Microbiologists with experience in nitrifying bacteria are going to be much more sophisticated in their hypotheses and explanations, but as with any thing in life, anyone can hypothesize. We're faced with problems everyday that we need to think through, not just aquarium keeping. Hypotheses are free, doing experiments to test them, that's another story!