Yes, in tanks with overflows, the filtration - whether it is a wet/dry, sump or refugium or some combination, is underneath the tank and the overflow is just a way to get the tank water there without doing it too fast or taking all the fish with it. There are two basic types of overflows. One is an "over the back" or hang on overflow added to tanks that are not "reef ready" or predrilled. Water basically goes in to a container on the inside of the tank, is sucked over via a U tube or similar into a container on the back of the tank which is connected by a hose to the wet/dry (sump, etc). In tanks with built in overflows, the idea is basically similar. Water goes through cut outs in the top of the overflow, drains down a pipe/hose into the wet/dry (sump, etc).
Originally Posted by Vanos
I've seen them installed on tanks in my local area but not sure how they work. Is the plumbing underneath the tank. i.e. wet/dry filter and protein skimmer underneath
THE OVER FLOW HOOKS UP TO THIS, A WET-DRY SYSTEM