If I had to take a guess, I would say it would be the rapid change of you kh values...going from 14 to 7 in 24 hours tells me that the tank hasnt stabilized yet. Whats the ammonia? I had the ADA Amazonia, along with PS and my ammonia was off the charts for about 2-3 weeks...it took about a month to fully have no ammonia or nitrites, and for the gh/kh to stabilize..How long has the tank been setup?