Squeak Squeaken

So while I was in the middle of putting up sale stickers for my department, I heard this odd high squeaky noise.
Which....I immediately realized wasn't a good thing.
There's a certain series of sounds that you grow used to in my department...or at least I grow used to, and so it's always jarring to hear a sound that 'doesn't belong.'

But I wasn't sure why I would suddenly be hearing this sound when I hadn't just moments before.
The only big difference was that my coworker had been gravel vacuuming some of our fish tanks, and now had put it all back. 

I could hear the sound originating from behind our fish wall.
So as soon as I finished the page of sales that needed to go up.
I went to investigate.

And quickly found the source of the sound.
The squeaky noise was coming from our Goldfish sump.
Which is basically a large holding tank that holds water for our feeder goldfish tanks.
And that sump...was basically empty of water.

What had happened?
My coworker had been gravel vacuuming the feeder goldfish tanks...and had done too much of a thorough job.  
Because the goldfish sump....it has a limited water supply that does not refill as quickly as the main water system's sump refills. 
So if you take too long gravel vacuuming...the water levels within that sump drops quickly...and doesn't refill. 

Which means that the motor running the water through the pipes...is basically running dry.
And therefore causing the squeaking noise. 

The solution was simple.
Fill the sump back up with water.
And the squeaking immediately stopped.

What I find interesting though....is that my coworker too heard the squeaking noise...wondered what it was...but didn't go investigate to find the source....
I wonder why that is...
Why did they not think to figure out where the source of the noise was coming from?
*shakes head*
No idea....

-Sarnic Dirchi