That depends on what you want to keep and what kind of 20 you have You can never go wrong with PC's, plus it allows for a lot of options. Do you have this tank up and running at the moment?
yes its up n running i have 20lb of lr some ls the coral i plan on getting is greenstriped mushroom bullseyemushroom,starburstpolyp buttonpolyp toadstoolmushroom leather and may be some anemone