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Re: What is "tank cycling"

John Guild asks:

> what exactly is "TANK CYCLING"?

John, it's a biological process where bacteria convert fish waste (ammonia) 
into less harmful substances.  Certain bacteria commonly referred to as 
Nitrosomonas species convert ammonia to nitrite.  Another category of 
bacteria commonly referred to as Nitrobacter convert nitrites into nitrates.  
(I'm being cagey about the names of these bacteria because there is some 
controversy over their scientific names.)  The bacteria reside in the tank on 
smooth surfaces such as the glass walls, the ornaments, the thermometer, the 
heater, and also on the inside walls of the filter box.  It takes about 3-6 
weeks (depending on temperature and the availability of oxygen) for the 
beneficial bacteria to establish themselves.  You can introduce these 
bacteria to the tank via a scoop of gravel from an established tank, or a few 
ornaments or plants from an older tank.  You can also establish the "cycle" 
by using the fishless cycle method, where drops of ammonia are used to 
replace living fish to provide the ammonia waste.  IMHO, the fishless cycle 
method is superior because it does not risk any fish's lives.  There are 
numerous websites that go into great detail about defining the cycle and how 
to do fishless cycling.  Here's just one of several of those sites: