yes nitrites

i'm cycling my tank too, but im doin a fishless cycle. i'm still very new at this but im sure the bacteria that turn nitrites into nitrates take longer to settle in rather than the bacteria that turn ammonia into nitrite.

there's no way to know for sure how much longer it will be... when doing the fishy cycle, the whole process can take as long as 6 months.. when doing a fishless cycle, the bacteria that turns nitrites into nitrates actually takes the same amount of time to get started.. the difference is that you may have seeded your tank when you just had ammonia in your tank, but most people don't re-seed when the nitrites start to spike. i tried this and it cut my cycling time WAY down.

Once your ammonia AND nitrItes have stablized at Zero (without water changes) for 5-7 days you are good to go for a fishless cycle.

In a cycle where Fish are involved it is a balance. I would advocate the same wait period before adding more fish. Traditionally, the suggestion is to add 2-3 fish (~4" worth) every 3-4 weeks. If you test during this process, you will see why as the cycle will burp each time slightly and settle back down and register 0's for a day or two by the end of the 3rd to 4th week. A very stressful process

BUT you must always monitor the water closely when adding fish and be prepared for those dreaded WCs...