I have grape caulerpa. When it "goes", I don't notice a cloudiness in the water at all. This is probably just due to a lot of water movement. It never quite all dies off at once. There is always enough that remains to grow more.
I also have some healthy Halimeda which do the same thing. It is more dramatic when Halimeda does it since they have such large leaflike structure. The "leaves" go white and disintegrate into small green dots.
I'm only running the MH
lights for 8 hrs per day. The actinics are on for 12 hrs per day.
To answer and earlier question..."going sexual" is a way that the algae reproduces. It is kind of a self-destructive way of spreading itself around.