Hi Fish Fam, Two days ago I re-homed 2 female guppies that had been living in my QT. The day after they were gone and the tank was lying empty I decided to put three drops of Dr. Tim's ammonium chloride in the tank to feed the BB, since logically there were no longer any fish producing waste for the BB to live on. This morning when I went into my fish room, I notice that the water has gone cloudy, and smelled faintly of sulfur/ammonia. I immediately did a water quality test. I get a reading of: .25 Ammonia, .5 Nitrites, and 40 Nitrates. This is a tank which was fully cycled reading 0-0-5 just three days ago. I think I should immediately stop "feeding" the tank with ammonium chloride. It looks like maybe I've started a mini cycle based on some quick searches of previous posts. But in my case it's completely fishless. What do you think my course of action should be? Should I just leave it and let it run back through the cycle? Should I do a small, medium, or large water change at all? I was looking forward to getting some new male guppies middle of this coming week, but now I may have to wait. How long should this take to correct? More info: 10 gal, gravel, 79 degrees, 20 gal sponge filter, ph 7.6, silk plants.