Hey Peri....

The non glow versions work becuase they cast a siloheutte against a background. They are still effective at any depth. However, remember the color spectrum. Greens, blues, purples are the last to fade and red, yellow, and orange turn gray in color first. Black and white (Cop Car) present a very strong silohuette!

As far as glow versions.. the key thing to remember is, just because they fade for us doesn't mean fish don't see them - they do - long after the "human" fade has disappeared.

Zooplankton and phytoplankton emit bioluminescence. So glow version offer a more natural environment for Mr Salmon. Not to mention he can see it a little better..

Hope this helps!