I'm new to this hobby and bought a 20/g tank. I'm trying to fishless cycle the tank, and having horrible results. I have followed the directions exactly but my ammonia readings don't change. I set the tank to 4ppm of ammonia, and it's been three weeks no change. What is going on? I de-chlorinated the water. The ph is 7.5. The GH 130 ppm and the KH is 80 ppm. I have an underwater heater keeping the tank at 85 degrees. I read somewhere that if you don't have the bacteria seeded it will not cycle, so I bought API zyme, and Cycle - still nothing. Please help. Maybe my tap water has magical properties that kill bacteria - I don't know.