Not enough light

[Skyjerk]

I noted in This thread that I was hoping to not need to turn on the HPS lamp in my grow room in order to save juice, but I am now getting a leaves starting to yellow and drop off.
They have been in the grow room for about 2 weeks.

This so far is limited to the Habs. The Naga plants seem to be less affected.

I think I'm gonna have to bite the bullet and turn that thing on.

These plants went from about 6 hours a day of direct sun, to 24 hours of MUCH lower intensity light. I was hoping to make up for the lack of intensity with more hours
of exposure.

Is this line of reasoning absurd?

My current calculations are that I've only got about 600 lumens per sq ft
in that room which I think is really low. The HPS lamp will bring that up to around 3000
which seems much more the thing, and perhaps I'll shut it off at night as well.

Any thoughts or opinions? Besides the value of using lumens vs lux vs candles or whatever to measure light, of course.

I know lumens is a bad measure, but its all I've got so its what I'm going by.

 

[AlabamaJack]

you would think the light would be a linear distrubition and strictly a ratio...I don't know....

It could be that light is not a linear absorptin (thus chlorophyl productivity) distribution with intensity...the absorbsion may be a log distribution which means that for each unit of light absorbed, the chlorophyl reacts 10X that amount....

pure conjecture here...

 

[Josh]

you would think the light would be a linear distrubition and strictly a ratio...I don't know....

It could be that light is not a linear absorptin (thus chlorophyl productivity) distribution with intensity...the absorbsion may be a log distribution which means that for each unit of light absorbed, the chlorophyl reacts 10X that amount....

pure conjecture here...

You just blew my mind.

 

[Skyjerk]

You just blew my mind.

He just said that it might not have been bright enough

Well anyhoo, I turned on the HPS lamp. Shouldnt take them long to recover.
Its certainly bright enough now. Its like broad daylight at high noon
in July in there now...
Now I just have to make sure that it doesnt get too hot in the grow room now.
That lamp also produces a lot of heat. With the door closed for 30 minutes
it went up up to 96 F. in there. I prefer to keep it in the upper 80's and humid.
Leaving the door open will make it harder to keep the humidity as high.

Its a balancing act :-)

 

[QuadShotz]

you would think the light would be a linear distrubition and strictly a ratio...I don't know....

It could be that light is not a linear absorptin (thus chlorophyl productivity) distribution with intensity...the absorbsion may be a log distribution which means that for each unit of light absorbed, the chlorophyl reacts 10X that amount....

pure conjecture here...

Thus accounting for dropoff in intensity vs distance, eh?

Obviously, some wavelengths scatter easier and sooner than others..IDK how that relates to light distance compared to say foliage/flowering growth though. Then there's thermal differences as well.

I know my seedlings dig it about 6-8" away so they don't fry while the larger plants like all the light they can get, even if nearly touching the tubes..

 

[teh purple penguins]

you said it's 400w? tell me if you still get flowers or if they drop off . thanks