I am doing a fishless cycle with 75 gallon tank with 2 Marineland Emperor 400 hob filters. I have been adding ammonia (from ace hardware). I am currently adding 3ppm of ammonia and it is gone in 12 hrs. I have been adding the ammonia once a day. The nitrite is at 5 ppm and nitrates at about 80 ppm. They have been at this level for about 3 days. Should I keep adding the ammonia daily until the nitrites go down to zero or cut back on the amount of ammonia added? Should I also do a water change since I have read you don't want the nitrites to go too high or it will stall the cycle?