Let's take a reef at 9am and then again at 3 pm in Fiji for instance.
At 9 am the sun is at a 45 degree angle and then it is right overhead at noon and then again at a 45 degree angle at 3 pm. The sun would be directly hitting the reef for the whole 6 hour period (sure a cloud might block the sun for a while, but there would still be a high par value even then) just at diferent angles.
With a 6 foot tank (halide between 6 to 10 inches from water) and one 250 halide there would be a couple of options:
1) most popular because all of the light rails I have seen move back and forth with only up to a min delay in between moves. the corals (as individuals, not as a group) would see light then very minimal light then light.......
2) get a light rail that moves the light across once in a day. the corals will only get a couple hours of intense light per day.
Make sense now?
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