You may want to make a new glass material or a new water material and edit some of the settings. For a good effect, make the material both very reflective AND very transparent. In real life we don't think that these two qualities work together in one material, but in Lightworks, they do!
Good luck! Oh, and it's always a great idea to get Dwight Atkinson's book if you are doing any moderate to serious renderings (which it sounds like you are.)
