During my initial cycling period I did 1 water change due to a slight spike. My ammonia level is pretty much absent now and it has been 7 days. I took a water sample to local store and he said there was no traces of anything, is this normal. He said it should have gone up again with nitrates in order to get bacteria growth and recommended that I feed the tank. Will the second shipment of rock take care of this? I'm new to this and want to make sure I'm doing it right.