I was hoping for some input regarding overflows. I’m asking for a friend of course because I promised the hubs never to go back to saltwater … . Let’s say someone was to build a 20x20x 9 shallow reef. Low maintenance lagoon style with maybe some green hairy mushrooms, a nem , GSP and mangroves growing out the top. What kind of filtration would be best if one wanted a sump. Is it better to drill and have an overflow or use an external overflow like the Eshopps one?
Pic included to give a vague idea of what “friend” envisions.
Thank you.