Hi all. I’m currently growing three photo period plants about 6 weeks into flower. I have a 1000k HPS light set to 750k. The room is pretty hot and the plants are showing some heat stress. I have an AC unit in the room (6’x6’ space). My plants are about 3’ tall. My question is, would they do ok if I lowered the temp of the light to 500k until they finish, or would that stunt them being this far along?
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Light levels for smaller grow
- Thread starter MattD
- Start date
RagWeedDWC
New member
My gut tells me lowering the temp to 500k would reduce yield, (One a side note, I did not know you could do that with a HPS light). I would look at alternative ways of cooling before reducing light in flowering.
Lights on during the night off during the day, If DWC ice in the bucket sort of thing.
Give us some pictures, that may help give you some answers.
Lights on during the night off during the day, If DWC ice in the bucket sort of thing.
Give us some pictures, that may help give you some answers.
Toker1
New member
Assuming you mean 1000w lowered to 750w... thinking about lowering to 500w.
Hard to answer this specific of a question with out specific information on the grow itself. Generally speaking, yes lowering the light intensity will mean slower growth rates. This is assuming all other factors are negligible.
just as a side note, dimming an HPS bulb will effect spectrum output. The bulbs designed for plants were not designed to be dimmed down. Also, over a long period of time, dimming bulbs will shorten its useful lifespan (MH is more quickly degraded when compared to HPS...but both will degrade much faster when dimmed).
Hard to answer this specific of a question with out specific information on the grow itself. Generally speaking, yes lowering the light intensity will mean slower growth rates. This is assuming all other factors are negligible.
just as a side note, dimming an HPS bulb will effect spectrum output. The bulbs designed for plants were not designed to be dimmed down. Also, over a long period of time, dimming bulbs will shorten its useful lifespan (MH is more quickly degraded when compared to HPS...but both will degrade much faster when dimmed).
I’ve always dimmed the bulb because 1000w was always too hot. I had dreams of having a larger grow space when I bought it 
I'm going to be switching to an LED light in the fall which should eliminate most of the heat issues. I’m going to leave the light at 750w to finish this grow. I’ll keep the AC going I’m order to get through it. Thanks for the feedback, always helpful!
I'm going to be switching to an LED light in the fall which should eliminate most of the heat issues. I’m going to leave the light at 750w to finish this grow. I’ll keep the AC going I’m order to get through it. Thanks for the feedback, always helpful!
Toker1
New member
No prob. So just doing some minor calculations, assuming a 5x5 foot space... HPS requires approx 50 watts per square foot. A good LED (not blu-purp) like a quantum board requires 35 watts per square foot. So for a 5x5 foot space, your 1000w hps will require 875w of LED (must be as efficient as a new quantum board or better). The heat savings there will be less than what you are running right now (750w). So it will actually be hotter running the sane set up with LED. Unless you dim the LED’s below the recommended light intensity of 35w per square foot.