freshwater tank conversion?

Hey guys atm I hhave a 180 g tank that's a freshwater I'm converting it to a saltwater tank, my question is how long would I have to wash it so all the copper is all gone? And is there any medicine to remove copper from the tank. And with 2 rena xp4 filter be enough for filtration I cannot make a sump iim going to put roughly 180 lbs if live rocks and about 2" sand bed.