Cycling

Pure ammonia will be better because it allows you to have much more control over the amount of ammonia introduced into the system. Rotting food will produce ammonia, but it may not be consistent or predictable and will likely stink. Just be sure not to use scented ammonia or anything like that. The cycle will be done when you can add enough ammonia to bring the level to 5ppm and the bacteria have it back down to 0ppm within 24 hours.

I agree. Usually, you can find a store brand labelled "clear ammonia" that is good for cycling. It can contain chelating agents, but shouldn't have any detergents or perfumes.

HTH,
Jim

There is a great sticky at teh top of the newbie forum that helps explain the cycle and how to do a fishless cycle. Yes, make sure to use pure ammonia (some have chelating agents and that is okay, but no scents or soaps or detergents).

At the end of the cycle you will have nitrates forming in the tank. So you should have a test kit for ammonia, nitrite and nitrate.