'beep'

For about three days in a row, I heard a slight 'beep' sound coming from my reef.  It happened exactly every five minutes, but I could not find the source. I'd set a timer, then run into the fishroom and stand near whatever I figured was causing the sound, yet had no luck after several tries.  Since I'd only get one tiny half-a-second to determine the source's origin, and when I couldn't would then have to wait five more minutes for it to happen once more, it became somewhat of a mystery. I wasn't about to spend all day trying to ascertain the object, though. I'd already checked the obvious culprits: it wasn't one of the smoke detectors, and it wasn't one of my computer UPS units either.

Beep.

Slightly annoying; it was a quiet sound. Hardly worth noting. Still, I decided to try unplugging both ATO systems, thinking it was coming from one of the two I use: The SmartATO Micro on the frag system & the ATK on the main reef.  While unplugged, the beep happened again. The ATO systems were innocent; they were eliminated as the cause.  

The weird thing was, it sounded like the sound came from behind the saltwater mixing storage container, the giant vertical poly tank.  There's nothing behind it though.

The next day I decided to check the power station, specifically focusing on the UPS that the Apex controller is plugged into in the event of a power failure. UPS devices need their batteries replaced on occasion, but unplugged and powered off, it couldn't be the source. Plus as I held it in my hands, I heard a soft 'beep' again, and the UPS re-installed. Whilst I was in that area, I decided to clean up the wiring which involved wiping down every wire with a damp sponge, and then re-routing them better and fix what looked like a tangled mess. Some are now coiled up and tethered with a smaller ziptie.  As you might imagine, this turned into a 90 minute project.  

I noticed the security alarm's camera on the wall with its little lights... and thought perhaps it was the source. I unplugged it. A few minutes later: 'beep'

Crazy! 

Besides the benefit of having a cleaned up powerstation with tidy wiring, I happened upon a missing bottle of Phosphate Rx I *knew* was in my fishroom. Score! And I also noticed the CO2 tank to the calcium reactor was reading almost empty, so I'll need to get that tank refilled tomorrow.

Finally though, I did discover the source of the beep. My alarm system's panel displayed a warning that the glass-breaking sensor needed fresh batteries, and then displayed "press # to silence" on the LCD. I never knew that was even a thing, but in the future when I hear that tiny sound in a few years, I can only hope I'll remember this day. :)