What is Zeolite?

I have no experience with anything I am about to say, only remember it from other posts. It claims it sucks up ammonia, which is may or may not do, so that when one has fish in the tank, and doesn't cycle it prior or do sufficient water changes, it makes the water less toxic for the fish.

I haven't heard that this works, and nothing beats fishless cycling and good old fashioned water changes.

If you don't know about cycling, read the stickies here, and it is easily googled.
cheers!

http://www.fishdoc.co.uk/water/zeolite.htm
http://mineral.galleries.com/minerals/silicate/zeolites.htm

Zeolite is an ion exchange resin that can remove some ammonia by exchaning the NH4- (ammonium) ion for the Na+ or Sodium Ion. Since it only works for Ammonium, zeolite is more effective in acidic water when more of the ammonia in the water is in the NH4 form. In alkaline water, zeolite will do very little to control Ammonia. Also due to its ion exchange nature, it can exchange other ions such as Sodium for Potassium making it not the perfect ammonia controling substance. This substance also gets fouled by organics and wears out relatively quickly. A strong biofilter makes a much better ammonia reducer than zeolite. I only use zeolite in emergency situations with waterchanges.