Fish Tank Cycling
Not so sure, I like the term 'fish tank cycling' as it makes me think of a fish riding a bike. Anyway it is the single most important issue with regards setting up a successful fish tank.
Too many people think that all is needed is to fill a tank with water and put fish in and that is that. Indeed there is a program on TV I have watched called tanked where they do just that and don't even mention the fact that a new tank needs cycling.
The problem is that fish produce toxins (mostly ammonia) directly from their gills, from their waste and from uneaten food. So if you put a goldfish in a bowl or a lot of fish in a new tank and they die a few days later, this is why. In a river or a stream pollutants just get washed away in the current but in a closed environment like a tank or a bowl, the toxins build up and the fish die. This usually unfortunately puts new fishkeepers off the hobby.
So tank cycling can be frustrating but necessary. There are two main methods, if you have experience you can add a couple of small fish to a large tank wile monitoring (and dealing with) the toxin levels until the tank can support the small amount of fish, then add a couple more and repeat the process. The advantages of doing this is that you will have fish in the tank during the cycling process, the downside is that it takes a lot longer to get the tank fully ready to support a full tank of fish. There is also the fact that despite your best efforts to manage the toxins, there will always be some to harm your fish.
The second preferable method is to do a fishless cycle which basically involves adding ammonia to a fishless tank and wait (about a month) for the substrate in your filter and elsewhere to build up (friendly bacteria) using something called the nitrogen cycle (actually the nitrate cycle) as the final part of the cycle nitrate to nitrogen is rarely employed. Instead nitrate is controlled through water changes.
The main downside of this method is that you have to sit and look at an empty tank for a month or so while the process completes.
The upsides are that the process is in actual fact much quicker with out fish as without fish to harm you can have the water temperature and ammonia level quite high without doing any harm. You can also add all your fish at once, although two thirds would be more sensible as it takes several months for a tank to fully mature.
Below I will include a 'cycling' article taken from the net that explains both methods for cycling a fish tank and below that we would welcome any comments or suggestions on this topic.