tide pool set up

Question
I'm the Director of Wildlife at the private non-profit Lake Erie Nature & Science Center. In our  exhibit hall is a molded fiberglass Tide Pool which has been giving us fits. I am starting over from scratch after having replaced the stainless steel dump tank with a plastic one. This should solve our water contamination problems we were having. My questions (two of them) are...
1. Our metal halide lighting consists of two 175w 5500K pendant bulbs which have to be hung about 3' above the water surface which is 1' deep in the deepest pool. From what I understand, this is barely adequate for most corals and other photosynthetic animals. I have recently heard that there are some corals (mushroom coral, non-photosynthetic gorgonians, Tubestra corals, bubble coral, tree coral, brain coral) that have little or no specialty lighting needs. Is this true? The question I'm trying to answer is do we need to spend the money to upgrade our lighting or are there enough corals available in the pet trade that dont require extensive lighting?

2.)I'd like to stay with a fairly corse substrate since the system has a water intake in the bottom that is screened off. Too fine of material will either pass through or effectively block the flow into the pump and filter. I'm considering crushed coral, aragonite or something called Arag-Alive (aragonite with bacteria in it). Do you have an opinion? and also, does it need to be regularly replaced?

Any help you can give me with these questions will be much appreciated.

Answer
Dave,
You are correct.  There are several species of low to no light corals and invertebrates that will do well under the lower lighting conditions you have.  I'd recommend upgrading the bulbs from 5500K to 10,000K bulbs to reach the deeper blue spectrums required by the photosynthetic animals.  Bear in mind that these animals while not needing as much light, they will require more water flow to stimulate feeding activities.  How far apart are these bulbs?  How big is the pond?

For a better understanding of these corals/invertebrates that you have available to you, I'd suggest picking up copies of Julian Sprung's Corals and Invertebrates: Quick Reference Guides.  They will give you everything you'll need to know about what you are looking to keep.  We have them available via our online catalog if you'd like more information regarding them.

To answer your other question regarding substrate, I'd suggest using anything that won't drain into your filter and chew up your pumps!  That being said, te Arag-Alive product will most likely be too small.

Best of luck with your tank.

Regards,
Scott Johnson
Aquarium Crazy Fish
www.aquariumcrazyfish.com