I had good results with filter plus manual white balance. How do you feel about that?
I've got Alex's magic filters (both the Green and Blue water) for the 8mm filter holder - which I've fitted to my 7-14mm so will try those for sure. My recent diving trips have been too deep for the filters, so hoping the relatively shallow Truk wrecks will be okay for ambient lighting / filters. I'm seriously looking at the Cyan bulbs for my Keldans also.