I have been cycling tanks, both saltwater, and freshwater, and had never seen this happening. I have been cycling a new system for a few weeks now. I have been using Dr. Tim's ammonia chloride solution. Every time ammonia falls below 1 mg/L I add some more to get the concentration around 2. I have been testing it with an ammonia test from Hanna Instruments and using strips from Lammote. On January 27th it was 1.99 mg/L, on the 28th 1.46 mg/L, on the 30th 1.99 mg/L, and today (1/31) it was >3.00 mg/L. The system is freshwater, but since I could not see how that would change the rationale I decided to post it here. Plus, I feel that we (reefers) tend to discuss chemistry more in-depth than the freshwater community. What do you guys think?