How long was the tank empty between Bettas? If it was more than a day or two the BB probably died off because there was no ammonia feeding it. I would do at least a 50% water change, wait an hour retest & do another 50% to get that nitrite down & I'd do 50% each water change. the cycle could go 6-8 wks depending on how much if any BB survived in the filter based on what you said it sounds like you are essentially starting from scratch with a fish IN cycle.
Last edited by shellieca; 12-17-2012 at 10:27 PM.