want to add sump

i am farely new to this hobby and was hoping for some advice, i added some more coral to my tank, so i have decided to add a refugium, right now i i have a wet dry sump about 24" by 12" would it be best to replace the wet dry or add it to the refugium in maybe a plastic container i was thinking of drilling some holes in my filter so it drains in to the container where i put some rock and sand is this a good idea or am i wasting my time.

Alslo when you sa "wet-dry", does that mean you are using bio-balls?

with the bio balls, I have heard that you should remove one or two a week until they are gone. 

check out http://www.melevsreef.com/ for good sump design ideas.

that would be real helpfull thanks