I don't use the collar to stop a behavior, instead I use the collar to get the dog to DO a behavior. So no, I wouldn't "correct" the dog away from the pool.
This is a management issue, you need some way to block him from entering the pool when you don't want him in there....or you need to be out with him and keep him away from it. You can't have it both ways, he's either allowed to go in, or not.
--Regina and the GSDs:
UCDX von Sontausen Holy Grail (The BUNNY!) HGH, UD,RA,BN,GN, ASCA UD RAX High in Trial
PAM Monster Mike SchH2,UDX,OM1,TD,RE,VER
PAM FGDCh Ianna von Sontausen UDX,BH,TD,RE,PT (4.26.1998 - 2.11.2013)