Hey guys I'm currently just starting a underwater scene. It is very basic right now, lots of things to add, tweak or fix. I know modeling the seed weed, or grass might be a better idea. But I was curious as to why I got this fog like effect with the caustics, and fur. I have an area light shining though a displaced grid to get the caustics. I also have an environment light in the scene as well. I'm using the new hair model if that helps. I"m rendering with PBR. All the settings are pretty standard. Thanks for the help in advance

Cool effect you got there!

You can also create caustics with different techniques, not sure if you are looking for that but..

You can assign a material with a noise to a light, dont have Houdini in front of me right now otherwise I would have provided an example.

What you also could do is render out a noise as an image sequence and then create a distance light and use the noise as projection map, should be really fast to create caustics like this.. + you can see the result instantly in the viewport..