What a horrible thing to have happen. Our dogs are our babies and I can't imagine losing one, much less two of them.
Dogs (even big ones) and inground pools really don't mix well.
Our neighbor has a beagle and a Weimeraner, and an inground pool.. they have a dog ladder, similar to the one on this page: http://www.doggear.com/dog-safety.htm
They have gotten in the pool with the dogs and trained them to use the ladder, so that they always know where it is in case they fall in.