Is that really true for aquarium application.
AFAICT it's true for all photosynthetic organisms. Of course nothing is really that simple..
Since a lot of aquatics are classed "low light" plants the chances of light saturation increases..This might be somewaht eliminated at lower intensity longer duration lighting.
Of course that is sort of the opposite of what one expected..
So if I had a large deep tank and put 8 fixtures on top that housed very cheap lowest output LEDs, but they added up to more PAR then 2 fixtures that housed very strong LEDS it would give me more "light penetration" then the stronger LEDs?
Generally speaking. The "high power" LED fixtures are usually lensed to concentrate the light. Also you have light attenuation through water (blue penetrates deeper than red) but that is sort of err very secondary.
100,000 lumen light pointed up and bounced off a ceiling will have probably low PAR value..
5000 lumens focused into a 2" spot will have Huge par ..in that 2" spot..
Power and geometry go hand in hand..
There is a Chinese brand of aquarium lights that use 90 degree reflectors and 1/2W emitters.. Need to find it. Would make a good comparison..