Refugium function

[SesameSeed]

Saltwater noob here. I've read about the importance of having a refugium, especially for reef/saltwater tanks. My understanding is that a refugium serves primarily as a home for organisms that act as biofilters, such as macroalgae and microorganisms. I have also read that they can be used as a home for Copepods, which can be a food source for some of the life in your tank. In all of the sump refugia I have seen online, the refugium is placed before the main filtration stage in the water flow. I'm wondering how the Copepods make their way to the display tank from the sump? Are they able to travel through the skimmer and filter media before making it to the return pump? Or are you supposed to scoop some Copepods out of the refugium by hand for feeding? Thanks in advance.

 

[salt2salt]

Pods are in every section of the sump. They are tiny and make their way to the DT easily. i've never feed my 5 yo, fat Mandarin.