Oh well, journey of discovery it its then! Perhaps going from fish tank fluorescent to sea in the space of 18 inches was an overly challenging lighting concept to achieve within the limits of the program, with the image limited further by the initial terrain/environment choice seeming too much like an aquatic environment instead of going the more conventional fish-tanky route. I took the time to try everything suggested in the original thread, and I got to play with parallel light cubes and a lot more light lab settings so it wasn't a total waste. Thanks for you time and input!