Do I need to ground my pool?
I never knew that pool rebar was grounded or bonded, so I did a search and found what looks to be a pretty good article on the subject:  http://www.poolspanews.com/2009/051/051grid.html

The lights in the pool may be 12V, but you've certainly got a transformer for those lights, a pump, and possibly other stuff in the pool area that is at line voltage, and you want all of these things and the pool itself to be bonded together and grounded.