Personally, I think everyone who owns fish should have one of these: http://www.fosterandsmithaquatics.co...54&pcatid=4454
Testing your water is the only way to really know if it has a toxic level of ammonia, nitrite, or nitrate. Using testing equipment can help you work out a schedule that will keep toxins from poisoning and burning your fish. When you get a larger tank that you want to cycle (please research the nitrogen cycle and how to cycle without fish) you will need this kit in order to determine how the process is progressing. Make sure you get a liquid test kit, not the dip strips--the strips are inaccurate and more expensive, they're a rip-off.
If your tank is not cycled the only way to remove the ammonia is through 100% water changes and thorough cleaning of the tank with hot water. Once your tank is cycled, you will not have to remove all of the water and clean everything out, 30%-50% changes once a week depending on the stocking and tank size should be all you would need.