I have been cycling my new 45g tank with fish in for about 3 weeks. I started it with Safestart and 5 giant danios. I have been testing the water daily and did 2 water changes when total ammonia levels reached .50ppm according to my API MTK. I now have detectable levels of nitrate (about 5ppm) and total ammonia is less than .25ppm and dropping (actually at .125ppm according to my Seachem ammonia test disks. Same test shows free ammonia level at 0.0ppm). I never saw any detectable level of nitrites, though. Is it possible the Safestart bacteria took care of the nitrites without my seeing a spike? Has the tank cycled, or should I wait to see the nitrite level rise and drop before assuming the natural cycle has taken hold?