I have installed your package and I have got it to work. Here is a run with my dredger-submatine added; here it is about 240 feet long (60 feet x 400% scaling).
But, what caused the black leaf-shapes among the refraction caustics?

Is there a way that I can switch the caustics off? In my experience in Red Sea diving I usually did not see caustics, and never in low-visibility British water.