Old PFO Website from 2003:
http://web.archive.org/web/200304221...ofit+Items.htm
"OPTIMAL REFLECTOR(Reeflector): This reflector is designed to mount perpendicular to the front of the tank. It is made with 95% reflective aluminum and will put about 40% more light into the tank than a standard flat sheet of reflective metal. "
"PARALLEL REFLECTOR : The parallel reflector is designed to mount parallel with the front of the tank using fluorescents. It is made with 95% reflective aluminum and will put about 25% more light into the tank than a standard flat sheet of reflective metal. "
Light Distribution for Optimal reflector:
Light Distribution for Parallel reflector:
Under the optimal reflector at 6"-9", the area with the brightest light is greater along the X axis.
Under the parallel reflector at 6"-9", the area with the brightest light is greater along the Y axis.
Thus, at 6"-9", it is better to mount Optimal reflectors perpendicular to the tank and Parallel reflectors parallel to the tank.
At 12", it looks like both should be mounted parallel.