The sump is a 40 breeder. The pump is in the tank behind the tallest rock. It pumps up over the canopy and goes down into 2 filter socks. Then through the heater and pot scrubbers. It drains back to the tank through 4 x 2" bulkheads. Both sides of the drain pipe are fully submerged using 90 degree elbows. The is a 1/4 inch hole in the top of each drain to allow air in and out. It's very quiet.