The Nitrogen Cycle

I have a new 20 gal. tank with java moss and elodea, gravel, etc. I already know there are several ways of "cycling" the tank, but, which is the best or fastest way of doing this. (I'm hoping to get the newts in by Christmas). Thanks.

Your question is analagous to asking how you can age wine the fastest. What you can do is make it start faster and jump start the process with gravel / sand / a filter pad etc. from an established tank. By doing so you will seed all the types of bacteria you will need. They will just need to adjust their population density to the available metabolite. Having said that, the process does take time and a source of nutrients. You can add a pinch of flake food, a very small piece of fresh seafood or forgive my bluntness a drop or two of urine. Sounds gross but remember it is sterile and totally harmles. I'd keep it to myself if I were you though because others in the house may revolt.

Could you use water from an established tank? (guessing no).

The beneficial bacteria live on surfaces. There are a few in the water, but it's more efficient to use some sand, plants, or ornaments (especially ornaments that have a rough or porous texture) from an established tank, rather than just water. See:
http://www.caudata.org/cc/articles/cyclingEDK.shtml

If the tank you are setting up is understocked (a newt or two in a decent-sized tank), you can set up the tank with a filter pad or ornaments from another tank and put the newts in a few days later. During the first month, you still need to monitor ammonia and nitrite, but unless you have uneaten food sitting around in the tank, it's unlikely that the levels will be high enough to be a problem.

Thanks for the advice.

How do you know when the nitrogen cycle is in place? (The tank "cycled")

Pretty simple process.

Ammonia waste is released into the water and the ammonia levels rise

Nitrosomas bacteria eat ammonia and their population will rise and the ammonia levels will drop

A by product of the above it Nitrite and those levels will rise over time

Nitrobacter bacteria eat nitrite and their population will rise and the nitrite will drop

A by product of this second step is Nitrate

Nitrate is the least toxic of the three and the concentration will rise over time.

Just because it is less toxic does not mean Nitrate levels should be allowed to rise above a few ppm at most. Consistently high levels are indicitive of overfeeding, underfiltration, or generally poor husbandry and will lead to stressed animals.

Nitrate is removed by the metabolic action of plants, water changes, and special bacteria that are generally not found in any concentration in normal fishtanks as they are anaerobic and require either a very slow flow chamber, a very deep substrate, or a plenum set-up.

The tank is cycled when the ammonia and nitrite are consistently zero.

Sure Jenn, take the short answer.

The newts at the store are only about 1.5"-1.75" long and my 20 gallon tank is about 3/4 full. Would it be okay if I got 3 of these newts and some more plants and/or an ornament from one of the store's established tanks? I'm also considering one of those bacterial cultures to help stimulate the cycling of the tank.