The pool is open all the time (except when it's thundering which I expect happens a lot in July). The life guards are on duty in general from 10 a.m. to 10 p.m. When they aren't there the slide is closed.
As already posted, it's open 24 hours. The lifeguards there and at the Poly went off duty at 8pm when we were there earlier this month (June 7-13). Slide closed when they left. It's an awesome pool!