They run to a common sump wet/dry filter that you DIY. All the plumbing is barb fitting and uses clear tubing you can get from the hardware store. Return is up top, overflows are on arms with a strainer and you can move them to do water changes and drop the water level. Look at the pictures and you will understand what I'm saying.
If I still have them I will cut ya a good deal on them, trust me.