cycling a tank is a question that gets asked every now and again so i have tried to put togther a start to an article on it
please add your thoughts, ideas or corrections that can be made to it
Cycling your new tank
Fish give off waste products (urine and faecal matter), these waste products break down into ammonia (NH3), which is highly toxic to most fishes, In your fish tank the level of ammonia can build up to toxic levels in just a few hours. So that new tank you just purchased can end up a death trap for your fish, this is usually referred to as “New Tank Syndrome” or NTS.
To avoid this you need to understand the nitrification cycle that occurs in your tank, this is the biological process that converts ammonia (waste products) into other relatively harmless nitrogen compounds. Fortunately, several species of bacteria do this conversion for you. Some species convert ammonia (NH3) to nitrite (N02-), while others convert nitrite to nitrate (NO3-). So the process of establishing bacterial colonies in the filter bed that convert ammonia to nitrite to nitrate is called “Cycling” your tank..
During the cycling process, ammonia levels will go up and then suddenly plummet as the nitrite-forming bacteria take hold. Because nitrate-forming bacteria don't even begin to appear until nitrite is present in significant quantities, nitrite levels skyrocket (as the built-up ammonia is converted), continuing to rise as the continually-produced ammonia is converted to nitrite. Once the nitrate-forming bacteria take hold, nitrite levels fall, nitrate levels rise, and the tank is fully cycled.
Ammonia test kits can be purchased from your local pet shop and if your test kit is able to measure it you've got too much (it can stress fish). An emergency action is to do water changes to reduce the danger.
There are 2 main ways of cycling your tank, the natural way with a few fish or fishless cycling,
Fish cycle:
Test kits needed ammonia (NH3) - nitrite (N02-) - nitrate (NO3-)
The most common way to do this is to place only one or two hardy and inexpensive fish in your aquarium, Some suggested species include: common goldfish (for cold water tanks), zebra danios and barbs for warmer tanks, The fish waste contains the ammonia on which the bacteria live. Don't overfeed the fish! More food means more ammonia!
Speeding Up Cycling Time.
The nitrogen cycle can be sped up or `jump started'' in a number of ways. Getting bacteria from an established tank is another way, a cup of gravel, floss or sponge from a filter or media from a canister filter already running on an established tank will work fine to kick start your tanks cycle. Running your filter on an established tank for a week or two will allow bacteria in the water to establish in it, then it can be moved to the new tank.
Remember when moving a filter or media to keep them full of tank water or the bacteria may die off and cause another ammonia spike when re setup. This pertains to cleaning your tank as well; washing the gravel or filter in tap water will kill off the bacteria causing your cycle to start all over again, wash in tank water/
Of course, there are many variations on the above that work. However, it is a bit difficult to give an exact recipe that is guaranteed to work. It is advisable to take a conservative approach and not add fish too quickly. In addition, testing the water to be sure nitrates are being produced eliminates the guesswork of determining when your tank has cycled.
Should ammonia levels become high during the cycling process perform a sequence of partial water changes, thereby diluting ammonia to safer concentrations to prevent fish deaths.
Recently, products containing colonies of nitrifying bacteria have become available at pet shops (e.g., TLC Smart Start, ``Bio-zyme'', ``Cycle''). In theory, adding the bacteria jump-starts the colonization process as above. Peoples experience with these has been mixed; some swear by them some say they don't work at all. In theory, these products should work however; nitrifying bacteria need oxygen and food to survive. So their effectiveness depends on its freshness or the way it has been handled since bottling.
Fishless cycling
To cycle a tank without ever adding fish. The role fish provide in the cycling process is simply their steady production of ammonia; the same effect can be achieved by adding chemical forms of ammonia manually (e.g., ammonium chloride).or by the addition of household ammonia, use pure ammonia with no aromatics or colouring added. However, it is a bit more complicated than using fish because the water chemistry needs to be monitored more closely in order to add the proper amount of ammonia on a day-to-day basis. 1 drop per 15 litres of tank volume can be added per day until ammonia level reaches 5ppm, this level then needs to be maintained until nitrite readings start to show then keep adding the ammonia until nitrate starts to show, once ammonia and nitrite levels are undetectable your tank has cycled and fish can be added. The cycling process normally takes anywhere from 2-6 weeks. At temperatures below 22C it takes even longer to cycle a tank as nitrifying bacteria reproduce slower at colder temps, so add fish slowly and allow the bacteria to catch up with the increased waste.
