What is the best orientation for Spiderlight reflectors?

[weaglereefer]

Perpindicular like this?

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Or parallel like this?

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[lilrobb]

Parallel for even distribution,
perpendicular for more spot lights

 

[weaglereefer]

Rockwork is currently centered in the tank like a ridge with room in front and behind. When I pick some more up that configuration will likely change to a standard rock slope. I found a site that shows the distribution of light, but it didn't mention which orientation the reflector was in, so it was kinda useless.