OK, at first glance it looks like we've got different answers here but, reading carefully, I probably just didn't define my terms clearly enough and so we all interpreted it differently. But all the answers may be useful.
I hear Rooster saying if we don't feed the bacteria some ammonia within 12 hours we have a significant set-back to cycling.
I hear Rabbut saying maybe we could go 24 hours and only suffer a day set-back.
BTT points us to a thread where Bignose cites some info that after a day without ammonia we could lose 5% of our bacteria, or perhaps only 1-2%.
OK, so part of what got me started on this was that famous Applied and Environmental Microbiology article (Aug '96) where Tim Hovanec showed that previous assumptions about which species of bacteria were actually responsible for nitrification were wrong. I was studying that article and noticed in his Methods section that he describes how he fishless cycles the freshwater aquariums in the experiment: to paraphrase.. "ammonia was added to each aquarium daily for 20 days and then every other day or so."
So after 20 days of adding (roughly 5ppm) ammonia, he stops bothering to add it every day.
To me, this jives nicely with what the Bignose info is saying... You put in your 5ppm Ammonia, wait 24 hours, don't replenish the ammonia.. at this point, if you measured, you would see that you begin losing maybe 1% to 5% of your ammonia-oxydizing bacteria. It doesn't crash with the whole population dying, you just begin to lose a small, steady percentage of your bacteria.
Now if you are at the early stage of building up to full AOB population, this sets you back. If you have already acheived full population (ie. can process to zero in under 10 hours) then it would probably take several days of no ammonia to do any serious damage to your AOB.
By the way, Hovanec also confirms that while the NOB (Nitrite Oxydizing Bacteria) population is significantly slower to develop, it is also slower to die if it is starved of Nitrites.
So what is the practical use of this information? One thing I was thinking was that it allows you, in the second stage of fishless cycling during the endless wait for the nitrite spike to go down, to only replenish ammonia every other day or so, allowing you to potentially see more down movement in your nitrite test. (each 1ppm of ammonia creates 2.7ppm of nitrite, so every time you recharge your ammonia you are flooding nitrite on the other end, making it harder to know how your NOB population is progressing.) [technically, this stuff doesn't really matter to our TFF practical system of fishless cycling I think, because eventually the NOB population will reach critical mass and suddenly your Nitrite test will show zero, which is the sign you are looking for.]
OK, so what do you think? Anybody follow this line of thinking? Am I being stupid or does it make sense?
~~waterdrop~~
/www.fishforums.net/content/forum/23...Is-A-Power-Cut/
