Do plants eat/use up lumens/light?

I'm trying to wrap my head around light and photosynthesis. Can plants share light or do they eat it up similar to water? Maybe they absorb the light and that's why they can't share.

I was running a 150 hps for 2 medium size plants in 3 gall buckets. I also supplemented with cfl. I felt like I needed more/better light so I purchased another 150 hps. This works out well because now each plant gets its own light and I can adjust the heights separately. I'm guessing that 150w per plant is decent. I have about 6000 lumens per sqft in my tent. My lights are approx 10 inches from canopy.

Chime in if you can shed some light on this topic for me, but maybe I already answered my own question

The leaves absorb the light; that's the energy it uses to convert the nutrients to complex sugars.

Sorry im wrong how i worded it, yeah potpimp is right.
http://scienceline.ucsb.edu/getkey.php?key=2610

Lumens measures how humans see light, it is PAR that measures how plants see light

hogbud said:

Lumens measures how humans see light, it is PAR that measures how plants see light

Click to expand...

Im sorry but i never understood the lumens thing. i know it works by wattage, but does the kind of light factor into that?