definitely not... the point of the refugium is to export nutrients (mostly in the form of nitrates and phosphates).. zoanthids are not going to do any of this for you.. All they are going to do is excrete waste and you will have to create appropriate flow and lighting for them.. The most common refugium addition is Macro algae like chaeto.. It consumes phosphates as it grows hence pulling them out of the tank.. Then when you have too much chaeto you simply pull out handufls and throw it away or give it to other reefers to seed their refugiums... By pulling it out of the fuge you are essentially removing the phosphates that the chaeto is holding within its tissue. The great thing about macro is that you can grow it 24/7 which increases your nutrient export over refugiums that need a realistic light cycle... The prettiest macro out there is probably dragon's breadth... Another "show" refugium would be mangroves which some keep but it is debatable whether they will export better than macro algae and mangroves are for a more experienced aquarist and they require more care... The coolest show refugium I've seen was a pulsing xenia fuge. However I cannot comment on its functionality because I don't know anyone running one nor have I experimented with one.. Ive read about it on RC and there are cool youtube videos of it..
the important thing about your refugium is that you want it to have a slower flow rate than your sump.. it doesn't sound like you will have that kind of control if your refugium/sump/tank are in a direct feed line.. Ideally you want your tank to overflow into your sump (the skimmer section), then you can plumb out into the refugium and plumb the fuge back into the return section of your sump...
