Hey guys I'm new and I need help with my 16 gallon tank! It's been up and running for 4 weeks now with 1 medium sized driftwood. I'm using ACE ammonia and it's reading 4ppm. I had fish when I first got the tank and now do not. I gave them away when I found out about cycling! Now I'm stuck, I have the heater at 84 degrease the water level 2 inches below so oxygen enters the water. And my PH is around 6.8. I have crushed coral bring it up. I'm reading O nitrates and O nitrites... I want to know why I don't have any of them... Oh I also have a bag of gravel from a healthy tank. Any help will be much appreciated!