A wonderful, easy-to-understand chart on cycling your fish tank! How to cycle your new fish tank. This explains exactly how to keep your water naturally clean and your fish healthy. It's called "cycling" your tank. This will make your tank maintenance much, much easier. You will have to do fewer water changes and have healthier fish! Cycled Aquarium: Ammonia: 0, Nitrite: 0, Nitrate: Under 20 ppm