Photosynthetically active radiation transmission

[salty joe]

I am building an algae scrubber for a reef tank and am trying to decide what material transmitts the largest percentage of PAR. My choices are to place the lights an inch or so from the algae with a clear shield, or move the lights at least 12" away to avoid salt spray/creep. I don't know a lot of physics, but I know that light intensity drops off in a hurry with distance. So I want to get the lights close. I can't afford exotic materials, so I guess my choices for the shield are regular glass, low iron glass and acrylic probably 1/8" thick.

Can anybody point me to a link or in a direction to determine what material will transmitt the highest percentage of PAR?


Thanks,
Joe

 

[Andy Resnick]

What is 'PAR', exactly (e.g., the wavelength range)?

 

[Bob S]

Table 3.1 in Photosynthesis (sixth edition, Hall and Rao, page 40) shows that all the various algae pigments (green, red, brown) have photosynthesis absorption maxima between about 420 and 650 nanometers (blue and red light).

Bob S