: I was in exactly your position at the 4 week mark in my fish-less cycle of my 75 gallon tank, though I was dosing to 3ppm ammonia. I've journalled every day of the process and have some notes to offer:
Day 13 Add last half bottle of Safe Start
Day 14 Ammonia = 1.0 ppm Nitrites = Zero Nitrates = 40-80
I thought maybe Nitrites were peaking and returning to zero in between my tests every 24 hours so I tested Nitrites at 12 hours--still zero, so scrap that theory.
I just kept dosing ammonia to 3ppm daily and did increase the tank temp to 80 deg. as an experiment.
Day 27 Ammonia = Zero, Nitrites = 2.0 Nitrates = 80-100 SOMETHNG CHANGED and I suddenly had nitrites.
Day 44 (today) Ammonia = 2.0ppm, Nitrites = 2.0, didn't test nitrates, obviously they will be rising.
At this point, the tank seems able to process both ammonia and nitrites at the rate of about 1ppm each per day. I finally had access to a sponge from a mature tank and placed half of it in each of my two filters to see if I can boost the process.
I think it's probably true the bacteria which produce nitrites are slower to develop. Since I expect to introduce three young goldfish, I'm going to try to get to where the tank can process that 3ppm dose of ammonia overnight to zero ammonia, zero nitrites.
My thoughts: Wait. Keep testing. I've never had a tank "skip" nitrites. People were telling me my tank had cycled despite the absence of nitrites but it would have been a problem had I introduced my fish at that time.