On a simplified level there are two main issues which determine the speed at which one can establish an adequate nitrogen cycle in a tank. The first is the number of nitrifying bacteria one has in the tank when one begins to cycle it. The more one has, then less one needs to add. Next, the level of cycling any tank develops depends on the amount of ammonia. However, it is possible to have too much ammonia as this will work against things.
How we get the initial bacteria in a tank varies. At the low end it is all up to nature which means that it will come from one of two places. The first is via one's tap water and from the air. Yes, there are nitrifying bacterial cells floating in he air. However, the majority of those naturally present will be in one's tap water.
The second potential source comes from our doing something to add bacteria. This can be accomplished in one of two ways. The first is by taking them from an established tank. his can be done by moving some filter media itself or by rinsing it out in the new tank, But the bacteria can be located all over a tank on hard surfaces away from the light. it can also be found in the topmost portion of the substrate, But this is limited to the top 1/2 inch of so. At about an inch deep there is no longer enough oxygen to support the bacteria. One can also move things like decor, rocks and live plants.
Live plants use ammonium (NH4) which is what is mostly in water when ammonia (NH3) gets dissolved in the water. Plants also host bacteria on their leaves and steps and even their roots. It is possible to have a tank with no plants be completely cycled by bacteria. However, no matter how many plants one might have there will still be some amount of the bacteria in the tank. The faster growing a plant is, the more ammonium it will use. Plants do not create nitrite and in the absence of ammonia they can use nitrate.
The next way one can get bacteria into a new tank is by adding it in the form f bottled bacteria. However, most of the bottled bacteria does not actually contain what a tank will have once it is fully cycled. The key to is is the nitrite oxidizing bacteria. The actual type of bacteria we need in tanks to handle nitrite are the Nitrospira species. These thrive in the lower levels of ammonia a tank produces. In waste water treatment and higher nitrite levels the bacteria that will thrive are Nitrobacter species. These thrives in higher levels of nitrite than we should have in tanks during cycling and thereafter.
The above facts about the nitrite oxidizers was discovered by Dr. Timothy Hovanec et al. In order to makes this discovery they had to invent their own probes to detect the Nitrospira and then figure it out from there. As a result they were able to get a patent on them. What this meant was that other bacterial starter products could not contain Nitrospira. They had to use Nitrobacter. What Hovanec et. al. discovered was that when a tank was actually cycled if one started with Nitrobacter they ended up with none or almost none of the Nitrobacter and had developed colonies of Nitrospira.
The discovery was made when Dr. Tim Hovanec worked for Aquaria Inc as their lead scientist. Aquaria owned Marineland products among other things. This company was bough out by a conglomerate, Spectrum Brands, and made part of its pet division which also owns Tetra. So, the patent rights which Aquaria owned was handed to tetra to make their product, Safe Start. This and Dr. Tim's One and only are the only two products which contain Nitrospira bacteria. So, if you want to use a bottled bacteria to jump start the cycle, the best options are from Dr. Tim's and Tetra.
Now that this has been covered, it is easy to understand that there are 3 ways to cycle a tank the fastesst by starting with the greatest capacity to process ammonia etc.
1. Add a big dose of bottled bacteria following the instructions for using it.
2.. Moving over enough bacteria from cycled tanks do to the same thing. But the caveat is any diseases which might be lurking in the cycled tanks will move over as well.
3. Start with enough live plants such that they and the bacteria on them can handles the ammonia. The plants will consume most of it using the NH4 and some bacteria will be there because some of the ammonia in the water will be in the form of NH3 and this will be used by the nitrifiers.
As I said this is the simplified explanation. There is more to it than this but for most of use the other factors are less relevant. Here are some examples.
-The bacteria need more than just the nitrogen compounds, they also nee things like iron, oxygen and inorganic carbon.
= The bacteria cannot be frozen nor allowed to be in water to hot. However, they will reproduce faster in warmer as opposed to cooler water. This is why the right bottled bacteria will live longer if refrigerated.
- The Bacteria can use two basic sources for inorganic carbon. One is CO2 and the other are carbonates and bicarbonates. These typically also make up the KH in our tanks. Some plants can also use these two things to satisfy their carbon requirements. More importantly, KH is what works to keep pH levels up and stable.
- The bacteria live in a biofilm which they create, Other microorganisms will also colonize this biofilm. The biofilm is how the bacteria attach to hadr surfaces. It also provides the bacteria with protection from a number of things that might otherwise harm it. But, being attached means the bacteria do not actively seek what they need, instead it must be delivered to it from the water passing through the biofilm.
- The most bacteria in a tank will be found where the best supply of what they need is provided. Often this is in the filter media, but it can be elsewhere depending on a number of factors. The bacteria is photophobic and the biofilm can help protect it from light, However, the best protection from light is to be in places where light is absent or minimal.
Due to the nature of what I have done in the hobby for many years, I often needed to cycle 5-8 tanks at the same time. I would set up tanks outside for the summer months. I would sell the fish I was breeding at weekend events in the vendor room and would bring cycled tanks for this. So, Instead of cycling individual tanks I would set up a bio-farm and cycle filters. This way I could add a cycled filter or two to a new tank and have it be instantly cycled and safe to handle a fill load of fish immediately.
My time to cycle filters for 8 tanks holding a total of 200+ gallons of water was 12-14 days as long as I did not make a mistake, which I did occasionally before I had the method down pat.
The key was adding ammonium chloride. In earlier years I used Dr. Tim's but that got pricey when used for 8 tanks, Today there are other options including Fritz Fishless Fuel for one or two tanks or the Fritz dry ammonium chloride in a big jug which is what I use. I will never finish that jug, but is was still a much cheaper way to go.
If one uses either Dr Tim's or the Fishless Fuel, it is important to realize that they use the nitrogen scale and most of out test kits measure using the Total Ion Scale. There is a simple formula for converting between the two scales like we do for miles and kilometers etc. You can find a good explanation and the conversions here:
https://www.hamzasreef.com/Contents/Calculators/NitrogenIonConversion.php
I hope the above helped. If you have questions you can post in this thread or even faster would be to send me a site PM.
