fish_n_vw said:A sump is a extrenal tank useually under the tank in the stand. It will have an internal flow from the tank and an external flow to the tank. You can use it as your filter or put your filter in it. Its also a nice place to put all your other equipment so your tank dosent have it in it.
are you asking to see the difference between sumps because i have three different kinds of over flow systems would you like pics?