i'm afraid i'm not familiar with the water fog thing, but we made the light rays in this using the same method i mentioned in your WIP thread.
(RGB fluid container with a spotlight shining through it. the spotlight has a caustics ocean thing gobo.)

YouTube - Cadbury's - Spots vs Stripes (Official 2012 Olympics Sponsorship Ad)

imo, the surface ripples in your first image post seems too repetitive and you lose the feeling of depth. in the cadbury's ad there is little surface visibility at what is perhaps a shallower depth. If you saw less surface ripple it might also make it easier for you.
just a thought.