Hi Badger,
Maybe, but i have found that spot light has problems of noise frequently. I will try this but with many doubts.
As to rainbows, sun dog, iridescence etc, however, are impossible to do without post editing, for me.
If i have them in this way, however, are not reflected in the water, this is my crack-head problem.

Greetings.
Note:
On the other hand i don't understand why TG does not render by default, these effects, others do. Perhaps there are software problems? I would like to understand why, given that in the past in the FAQs they also spoke of these things.