If all the previous owners used were chlorine pucks, you may have a high CYA level, which means you may be needing to shock @ chlorine levels higher than 15.

If you have a pool store nearby, let them test your water, but don't let then talk you into buying anything. However, if you have a high copper level, you will need a metal sequestrant. That you should get while you are there.

Good luck,

CaryB
Go 'Canes!!