So, I have a tetra whisper 60 running, actually 2 of them. The newer one is only about a month old. Yesterday, it started making a horrible noise similar to that of a garbage disosal. It isn't constant, sometimes it goes into whisper mode. But, it did keep me awake most of the night from the noise, and my cat didn't like it much either. So, today I took off the intake tube and impeller and cleaned it off, I shot compressed air into the motor area to see if sand maybe was in it. It still makes the noise. Whats wrong? I need an answer sooon, as the one isn't enough to keep my tank sparkling clean for long.