what type of bulkheads work best for a 65 gal tank ,with overflow,i plan on setting up a reef system,my plan is overflow box > bio filter sump with protein ,skimmer> back to tank,
On a 65 gallon tank, I would recommend the Sch-40 bulkheads (black), that are available from Marine Depot... if one of your LFS's (local fish stores) don't carry them. (see link below) You don't really need the "Heavy Duty" or Sch-80 on a tank your size, but they wouldn't hurt either I guess... just cost more $$$.