I'm waiting till it goes to 1, sometimes it goes a little below depending on where I catch it, and dosing it back to 4, just like the guide says to do. There is no ammo in my tap water, or at least there was not last time I cycled this tank a little over a year ago, so there shouldn't be now. I did check yesterday, my ph did tank. Maybe that's it, but it's still converting ammo. I've been debating for a few days letting it go to zero, doing the water change, and putting in some fish. This tank took a few days over month last time, though I had a different filter, and no seeding material at all. I realized I may have a friend with some, so if I can get some, I'll probably go this way.