snrub, do you mind shooting a picture of your pond with the black dye in it at concentrations that you find pretty ideal? (point where you feel you don't have to add any more in to get the desired color)

I'm curious how dark the water has to be to get the desired effect. A close up may not be that helpful, I'm thinking more a shot from 100-200' away to get the whole idea of the color.

Only if you have time...