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Re: T-8 Light and Ballast Questi



The advantage of the McDonald's Arch shape is this.  A parabolic shaped
reflector has the unique property that the virtually all the light that
strikes the reflector is refelcted directly forward.  this is due
simply to the curve and placement of the bulb and the fact that the
angle of reflection is equal to the angle of incidence.

But curved refelctors are much more expensive to make than ones made
with several flat sides of increasing angles.  Given all of the factors
effecting the amount of light reaching your plants, the difference
between a true parabolic reflector and a many sided approximation such
as AH Supply sells is probably negligible.  

As a general rule of thumb, the flatter the reflector, the greater the
spread of the reflected light.  The more curved, the less the spread
until you reach a parabolic curve, after which the amount of light
reflected back and forth in the reflector increases--less makes it out
to your tank.

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