Darcy, not brave lah. Grey Sharks are very safe, if not a little shy. I would be worried with a school of Tiger Sharks, which have been sighted solo in these waters with some regularity.
Antacid, not sure about the magic filter. The water visibility was good, but some shots maybe too deep for the filter. I think even with good sunlight and visibility you need to be about 20m or shallower? Most shots were at 30m.
As with most diving, a good local dive guide usually makes the difference between a good and a great dive. PM me if anyone is interested in going and i';ll keep you updated on a 2010 trip.
Eudon