Disclaimer: Follow at your own peril!!
Before I start, I would like to remind anyone who reads this not to believe everything the seller at your Local Fish Store (lfs) say when they tell you that the fish can be introduce straight away. Beware of products in the market that states using its product and you can introduce fauna straight away. Don't believe a word of it. Firstly, a good lfs will never tell you to introduce fish straight away into a tank that has not been cycle. Products that states fauna can be added will always have an asterisk beside it. It will state along the lines of "when water parameters are met".
What is Cycling?
Nope, this does not involve pedals, chains or a handlebar. Rather water cycling (nitrogen cycling) refers to a process where ammonia is converted to other forms till it's deem harmless. I'll make it easy to understand hopefully. Ammonia is produce by fish waste, uneaten fish food, dead plants etc. Ammonia is toxic. Try swimming in your own poo and see how you feel.
Anyway, once bacteria aka beneficial bacteria(BB) is established, ammonia converts to nitrite. Now what's worst than ammonia is nitrite. Both of this kills. Another BB digest and converts it into Nitrate. Now nitrate is harmless but of course in high quantity, it can stress out your fish and in the long run cause health problems. Nitrate can be absorb by plants. the best plants I come across is frogbits. Now how to remove nitrate. For planted, no need to; the plants does it for you. For freshwater, water change (WC) Simple.
It takes anything between 4-6 weeks to complete this cycle.
Just note that water cycling is necessary. Introducing your fish without it will harm your fish and most than often, kill.
How to Cycle?
There are a few ways to do it actually. What the tank need is ammonia to kickstart. I'll not go into much detail on these as they can be easily found all over the web. Much more in depth explanation.
1) Fish Cycling
Considered a little inhumane. Depending on size of tank, a few fish will do. Hardy fish such as platy is okay. Most of the time they will survive but you are exposing them to health problems and you get fish disease; you'll then have a new set of problems in your water if that happens.
The fish produce waste and the cycle begins.
2) Fishless Cycle
There are number of ways to do this. One is to add pure ammonia. A pinch of fish food daily. Or you might not even need to introduce ammonia. Some aquasoil which is used for a planted tank has ammonia in them. Some are relatively high with ammonia. Hence, fishless cycling is the way to go.
Now there is one other method which is fastest but personally one should learn the very basic first and then learn along the way.
a) Ammonia (Fish waste, uneaten food, dead plants or roots)
b) Nitrosomonas (Bacteria) becomes present and converts Ammonia to >>
c) Nitrite (Deadly even in low quantity)
d) Nitrospira (Bacteria) becomes present and converts Nitrite to >>
e) Nitrate (tolerable to fauna in low levels)
f) Water Changes removes part of the nitrate in water, plants takes in nitrate, if anaerobic conditions are met, like possibly in the substrate, nitrate will convert to nitrogen and is release through the surface.
The process repeats. Now I recommend that if you are beginner, don't try chemicals on the shelf. Do it the simplest way to cycle your tank.
Tips
1) Be patient. We all know how it feels when one first sets up his/her tank.
2) Do not add chemicals you have no idea about.
3) Go fishless cycle instead.
4) Get a test kit. Use it on the first day and then once every week. Record your finding in an excel.
5) When the parameters are right, you will see your test kit readings something like Ammonia: 0 Nitrite: 0 Nitrate: 20. This is fine. You can add your fauna.
6) Small water changes now and then is better then one huge water change weekly. Unless you are dosing EI.
7) Never introduce so many fish at one time. Do it gradually. Your BB needs to catch up.
Mazlan's Version
I did fishless cycling. Example, Using an Eheim Pro 3 cannister as my filter. Now I did not add any ammonia as the soil had great amounts of it. Every week, I added Water Life Bacter. As I was using the Bacter, I did a test recording every 2-3 days. On the third week, the tank was cycled!
Now again I implore, do not do it this way. I added fauna slowly after the cycled as I had to be sure there was indeed enough bb colony. Do the basics first then gradually learn the other methods. One other way is to take mulm from another matured tank and place it into your new tank.
Well, cycling is not at all difficult. the only thing you must have is a lot of patient while the BB colonises.
Well have fun!
