Advance Series aquarium sumps are designed for the necessary versatility of the advanced aquarist. These ingenious products are two-in-one combos: allowing for the aquarist to combine two sumps into one. This versatility allows you to create a refugium in one side, as you place your skimmer in the other. The possibilities for aquarium accessory hookup are endless inside this must-have sump. Each one includes a drip tray, filter pad, egg crate, light stand, 1" bulkhead and 3 ft. of 1" flex hose.