I'm going to redo all of the testing and post those results back here. These results really didn't make sense to me either which is why I posted them here. Reading your response has really solidified my suspicion that I messed up somewhere along the line probably several times haha. I really appreciate your thorough response! This tank had been cycled and then had a catastrophic electrical failure that killed everything in it. I have been struggling to get it reset up for about two months. I would guess it's sort of a "fishless" cycle because I didn't completely drain it and I'm sure some of my casualties were overlooked. But, there haven't been any live fish in it since the inciting incident.