Do plants require a period of complete darkness?

[tyrophagus]

I have an LED lighting system and I can leave the lights on at night at a low setting. I have measured the PAR level at the surface at 2 which is very low.

Do plants need total darkness and can algae use this lower level of light?

 

[sanj]

i would have thought it would be ok from the plant perspective, 2 PAR at surface is too low for plants to photosynthesize.