Put a couple drops in, and then test the water to see if it is up to 5ppm. Once it is up there, let the tank sit for a couple of days at 85 degrees, then test for nitrites. You should start to see nitrite readings after a few days (3-5), keep the ammonia levels up at 5ppm until you can add the ammonia and have it disappear in the readings. Do a large water change, then you are ready for some fish! (one at a time of course!)