Elite Ghost Overflow Box Small Sevenports Nano Aquariums One of the top reasons cats stop using their litter box is simplebut often overlooked: cleanliness. Many cats are incredibly sensitive to odors and dirty litter, and if the box isn't hygienic looking into overflow boxes, one that I will drill a hole top center of tank to the sump any suggestions? first time setting up a sump and a little overwhelmed. : r ReefTank Bud Stewart Lure eBay Guide to the National Park Service Oral History Collection (U.S. National Park Service)