Protein Skimmer Delay Timer by Reef Octopus. Perfect for making sure an HOB skimmer doesn't overflow when power is interrupted. $30 plus shipping.
See more about it here: https://www.bulkreefsupply.com/protein-skimmer-delay-timer-reef-octopus.html
See more about it here: https://www.bulkreefsupply.com/protein-skimmer-delay-timer-reef-octopus.html