I'm assuming you're at Francis Marion University, and I imagine you guys like pool parties because it's hot. What about contacting the Country Club of South Carolina? Their Website says they are a resort too, so you could rent out a room for movies and snacks, but also use the pool and tennis courts.
http://www.countryclubsc.com/hospitality.html
I'm sure there are other country clubs in the area with pools, too. If you need a member sponsor, contact local alums who might be willing to host you guys since you are such a small chapter.
Good luck!