Define photoperiod with ramp times

[twilliard]

Hi all!
Its a question that has been lurking in the back of my mind.
Photoperiod
I am looking for the definition of this?
Is ramp time included in the total photoperiod for tanks.
OR is photoperiod only when your channels hit and stay at peak time?
Lets say channel 1 starts at 8am and ramps to 60% at 9am. 60% is held for 7 hours then ramps back down to 0% at 5pm
So is this 9 hours of photoperiod or 8 hours?
Thanks all!

 

[kschweer]

I think it may depend who you ask, but my definition of photoperiod would be from when the lights go on until they go off. So in your scenario I would say the photoperiod is 9 hrs.

 

[TheEngineer]

I agree with @kschweer

 

[Dtackett]

its more difficult to explain how that works. if youre ramp is so low that none of the light is usable for the plants then that's not counted in your photoperiod. easiest way to put it, is if it works, youre good. difficult way would be for you to get a par meter find the point where the light starts to become usable then on ramp down find the point where the light is no longer usable.

 

[twilliard]

its more difficult to explain how that works. if youre ramp is so low that none of the light is usable for the plants then that's not counted in your photoperiod. easiest way to put it, is if it works, youre good. difficult way would be for you to get a par meter find the point where the light starts to become usable then on ramp down find the point where the light is no longer usable.

Thank you I am a logical thinker and that makes sense.
I always wanted to test my par numbers

 

[Dtackett]

most clubs have a par meter. one of my lfs will actually loan his to you with nothing more than a deposit that he returns when you bring it back.