I'm a nervous nilly. I have EcoBAK running in my tank, a Phosban about 60% full. Its fully fluidized on one side and on the other, it looks like its moving very, very slowly. The tank is about 4 months old. For the last 4 weeks, 0 nitrates and phosphates. Over the last 3 or 4 days... nitrates are making a return. Should I worry, should I check something, or should I cool it?