MH light supplement from side ofacrylic tank?

I have a 150 gallon 30" deep reef tank with a single 250 watt HQI
pendant, and about 500 watts of VHO lighting. I have no room in the
hood for any additional (or higher wattage) lighting. I would like to
be able to supplement my current lighting to help color up some of my
higher-light requiring SPS, and reach the bottom of the tank where I
have a Crocea clam. A thought crossed my mind about the possibility of
adding a 400 watt pendent light from the ceiling surrounding the tank
and pointed at one side of the tank and striking the acrylic at about a
45 degree angle. I would guess there would be some light loss due to
the angle of light striking the tank (anyone know how to calculate
this) but are there other factors why this might not be a good idea.
The pendant would about 3 feet from the side of the tank so I would
guess that warping or damage to the side of the tank would be unlikely.