Doing a fishless cycle and have a couple questions. Tank has been set up for eight days now. I am testing the ammonia daily. When it goes away I will add some more to get it up to about 4 ppm. Then I will wait unitl it goes down again and keep adding until it goes away in about twelve hours. ThenI plan to test nitrites until that is good. Problem is the ammonia seems stuck at about 1.5-2.0 ppm. What is the deal with that or is that low enough to add more to bump it up again?