I am sorry, but this is simply not true. I know the chemistry involved. However, there is also a limit to how much ammonium (NH4) fish can handle.
It is also not true that nitrification stops in acid water. What happens is the bacteria involved will have receptors for NH4 instead of or in addition to those for NH3. Also, plants use ammonium and nitrifying bacteria mostly use ammonia (NH3). However, nature is pretty good at how it works and that is why some bacteria are able to process ammonium. Bacteria process NH4 less efficiently than NH3.
I have come to believe that almost no fish keeper should ever do a fish in cycle. Most who believe they know what they are doing in this respect actually do not. They end up harming or killing fish. While I wrote two articles on how to deal with a fish in cycle gone wild, I will no longer help people who use this method. I will refer them to my artciles. If you do not know the answers or how to calculate the answers to the following, you should probably not be doing a fish in cycle.
1. How do you know how much of a total ammonia reading is in each form- NH3 and NH4.
2. At what level does NH3 start to become toxic to most fish?
3. How much ammonium can fish live with, and for how long?
4. What is the difference between the nitrogen scale and the total ion scale.
5. How does nitrite harm/kill fish and how can this be prevented without doing any water changes?
8. How does one do diluted testing and when is this needed and why?
I am willing to work with anybody to help them complete a fishless cycle. I have done this a number of times over the years and it always works. Without any help from seeding a tank or having live plants, it will take 4-6 weeks to fully cycle a tank without using any fish. How long actually depends on how much bacteria one has at the outset. The answer is, whatever comes in via one's tap. This is highly variable and cannot be determined in advance. And this fact accounts for the difference between 4 and 6 weeks. It also assumes one makes no serious mistakes along the way.
My favorite thing in temrs of helping with cycles was a couple of years ago when my fish club worked with a local 4H group. We worked with a dozen kids in the 10-12 year old range set up their first tanks. Their parents were also involved. This was a summer project that had only a few months to run. My contribution was to provide each 10 gal. tank with a fullly cycled foam filter and mulm. I did this in about 2.5 weeks
Imagine if these newbies had needed to cycle/establish their own tanks. The club supplied all they needed- tanks, lids, lights, filters, air pumps, thermometers, substrate, decor, dechlor live plants, fish etc. We did teach them about the cycle, but did it for them this time.
