Keeping deep water species

[BlackOnyx]

What's considered subduced lighting like 100ft down.

[Pandora]

You could get moonlights to simulate subdued lighting...

But what kind of species are you thinking of? 100 feet down is not really deep sea. The continental shelf hardly ends at 500 feet most places, and a lot of what we consider "true deep sea fauna" exists at depths of thousands of feet! At those depths, light is the easiest thing to simulate; it's the extreme pressure that will be very difficult to reproduce in a tank.

[Wryknow]

I would run actinic VHO bulbs depending on what you are trying to keep. There really is a fair amount of light in tropical waters at 100' but it is almost all in the blue spectrum. This won't be enough light for invertebrates that rely on photosynthesis for energy though.

[BillnJennh]

I would think that there would be very little if any photosynthesis in deep water species, therefore you could probably run about any kind of light that is not too garish (like lemon yellow).