One new and never used AutoAqua Smart Skimmer Security ($55), or one used AutoAqua Smart Skimmer Security ($45).

SKIMMER SECURITY MADE SIMPLE
Smart Skimmer Security by AutoAqua uses the uniquely-designed contactless optical sensor to prevent the protein skimmer from overflowing. No moving parts to service or fail making this unit incredibly reliable. A magnetically coupled sensor makes it super easy to install and adjust the desired level in the collection cup.

No need to purchase new lids or DIY modifications to the collection cup!

As the level in the cup gets too high, Smart Skimmer Security will shut down the skimmer immediately to prevent your skimmer from overflowing. Auto time delay (5 minutes) function prevents false alarm due to power outages.

A magnetically coupled optical sensor mounts to most skimmer cups up to 1/4 inch thick.

No DIY modifications to the collection cup are needed for installation
Plug&Play – automatically recognize when mounted
Unique magnetically coupled sensor
Extremely simple to set up
Auto time delay

SMART SKIMMER SPECIFICATIONS:

Power Input / Output: 100 ~ 240VAC, 10Amp
Max Power: 1100W for 110VAC / 2200W for 220VAC
Max Mounting Thickness: 1/4 inch (6.4mm)