sump info needed

[smbuddy46]

i'm new to this. what is the purpose of a sump are these used basically on larger tanks. are they just another type of filtration. is this something that is placed below the main tank for the water to flow into. so basically with the overflow of the water what's on top is what is filtered. am i right, it is used with any other typw of filter system. thanks

 

[golfish]

lots of reason for a sump...Without one I'd have to have my heater in the tank, a hang on the back skimmer (they don't make a good HOB skimmer) I'd have to have probes and and lines and powerheads and all kinds of ugly stuff in the tank...A sump is really not used as a "filter" although some people may have some types of filter media in the sump..