My ammonia is spiking out of control. I am in the middle of a fishy cycle, and my ammonia is spiking from 1ppm to over 8ppm in 24 hours. I have done 75% changes two nights in a row to get it down, but the next day it spikes and is up to 8ppm again. This came after about a 2 weeks of sitting relatively low (1-2ppm before changes). I got about 10 pounds of cultured gravel from my lfs. Is it possible that all the bacteria died and is contributing to the spikes?