IMO I can't think of a situation where
PCs would ever be considered high light.
I can only speak to the tank/light combos I have had and what I consider H/M/L light. I have a 29 gallon nano with 103w of
PC lighting. The tank is (i think) 16" tall. I consider the top of the rockwork medium light and everything else medium-low to low light. I had a 12 gallon nano as well that was (again, I think) 12" deep. At first it had 48w of
PC lighting which I considered medium pretty much top to bottom. Then I switched to a single 150
HQI metal halide about 8" off the water. I would consider the top 8" as high light and the rest medium-high. I also have a 120 that's 24" deep. First I had 2x150w
HQI metal halides. The lights were 12" off the water. I considered the very tip top of the rockwork to ne high to medium high light (there were high light corals that I would not have kept up there), and the bottom 16ish inches to be medium light. The very bottom, on the sand I would call medium-low. I now have 2x400w
metal halides and 2 54w
T5s. I consider it pretty much high light top to bottom. If it were a 30" tank, I'd have called the bottom 6" or so medium to medium-high light.
