Leaf temps 10°F lower then tent temp?

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GarageGardener69

Well-Known Member
Yeah so I have an ink bird set to 75°F and I have this laser temperature gun, good quality, trust it’s readings.. I’ll zip the tent open real quick and point it at the leaves.. 62-64°F.

mind you this is being exposed to much colder air (~40°F) for a short period of time while I maintenance/water etc..

Took a temp reading on leaves before I closed it up. 50°F which I expected due to the cold air exposure.

Running under a HLG320 led kit

so if the air is 75 why are leaf temps so low at 62-64? I know they are a little cooler than their environment but that much?

I have had it set to 80°F in the past because I’ve read that temps 80-84 under led are alright, however, I don’t want to run my heater that much and 75°F is a much more achievable temperature that stays pretty stable.

Thanks
:eyesmoke:
 
G

GarageGardener69

Well-Known Member
Also, isn’t one only good for veg and need a different light for flower? HID CMH or am I confusing them with others? I just went right to HLG lights and am happy
 
PJ Diaz

PJ Diaz

Well-Known Member
Leaves transpire, and LED lighting puts off very little infrared light (radiant heat), so it's typical for your leaf temps to be lower than ambient with LEDs. With HID lighting, there is a large amount of infrared energy hitting the leaf surface, so you will have higher leaf temps compared to ambient. Personally I run a combo of CMH and LED.
 
PJ Diaz

PJ Diaz

Well-Known Member
GarageGardener69 said:
Also, isn’t one only good for veg and need a different light for flower? HID CMH or am I confusing them with others? I just went right to HLG lights and am happy
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CMH is a type of HID lamp. Other types of HID lamps include HPS and MH. You can look up the acronyms if you like. All HID lamps come in varying color temps. Generally speaking you want higher color temps for veg and lower for flower, but you can also run the same color temp all the way through.
 
Onextremebuzz

Onextremebuzz

Well-Known Member
rmax said:
Why not?
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Because his plants are in soil and they sit in a tent in a garage. If that floor is cool it's barely going to make a difference in his leaf surface temperature, not by that much anyways that's a direct result of the way the led works. That's why you generally run led rooms warmer then HID.
 
G

GarageGardener69

Well-Known Member
Lol my tent is in an insulated box. Floor is 3” thick foam insulation board R14 in value. 3.6g organic soil pots on risers in a tray, on a spinning platform so I can water and maintenance them.. I know enough not to have them on concrete….. also know that leds have an effect of even lower leaf temps because of heat output from light. Just didn’t think it’d be 10+ degrees difference
 
Onextremebuzz

Onextremebuzz

Well-Known Member
GarageGardener69 said:
Lol my tent is in an insulated box. Floor is 3” thick foam insulation board R14 in value. 3.6g organic soil pots on risers in a tray, on a spinning platform so I can water and maintenance them.. I know enough not to have them on concrete….. also know that leds have an effect of even lower leaf temps because of heat output from light. Just didn’t think it’d be 10+ degrees difference
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Learn something new everyday. What would really help is a cheap space heater on low power. That little 200 watt heater is probably costing you more money and you don't even know it.
 
G

GarageGardener69

Well-Known Member
Onextremebuzz said:
Learn something new everyday. What would really help is a cheap space heater on low power. That little 200 watt heater is probably costing you more money and you don't even know it.
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And the wattage draw on low would be…? 200watts running for all of maybe, 3 hours total a day. Does not cost much at all. Pretty sure I broke my costs down to you in another post not too long ago…. Not counting the Pennie’s here tbh
 
Onextremebuzz

Onextremebuzz

Well-Known Member
GarageGardener69 said:
And the wattage draw on low would be…? 200watts running for all of maybe, 3 hours total a day. Does not cost much at all. Pretty sure I broke my costs down to you in another post not too long ago…. Not counting the Pennie’s here tbh
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I maybe run my 750/1500 watt heater an hour a day tops on a cold day and never during lights on. I mean you did say you did not want want to run that heater that much and it's a 200 watt heater so that would tell me your counting pennies. And yes you did tell me before I fully remember. The plants will still grow it just won't be optimal until the warm weather hits. And cold shocking them isn't the greatest thing either but again they'll be fine. Also if the shed is that cold unless your running 24 hours a day (which I think you are can't remember) then there's no way that heater is only running 3 hours per day.
 
Turpman

Turpman

Well-Known Member
Are you using your laser to check tent temp? Just check something that is in the tent not under direct light. Maybe one of them is off, most likely. Plants leaves usually run 1 to 4 deg.cooler than the air temp. Lower is good it means the plant is transpiring.
 
PJ Diaz

PJ Diaz

Well-Known Member
GarageGardener69 said:
Lol my tent is in an insulated box. Floor is 3” thick foam insulation board R14 in value. 3.6g organic soil pots on risers in a tray, on a spinning platform so I can water and maintenance them.. I know enough not to have them on concrete….. also know that leds have an effect of even lower leaf temps because of heat output from light. Just didn’t think it’d be 10+ degrees difference
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Maybe your two different temp measuring devices are not calibrated?
 
PJ Diaz

PJ Diaz

Well-Known Member
Onextremebuzz said:
Because his plants are in soil and they sit in a tent in a garage. If that floor is cool it's barely going to make a difference in his leaf surface temperature, not by that much anyways that's a direct result of the way the led works. That's why you generally run led rooms warmer then HID.
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I'm not certain, but I'd be apt to believe that insulating the pots from a cold floor would help with overall plant temperature, including leaf surface temp. I've definitely noticed that bottom heat using heat mats helps to increase plant metabolism.
 
G

GarageGardener69

Well-Known Member
Turpman said:
Are you using your laser to check tent temp? Just check something that is in the tent not under direct light. Maybe one of them is off, most likely. Plants leaves usually run 1 to 4 deg.cooler than the air temp. Lower is good it means the plant is transpiring.
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no. Just different surface areas in tent. The guns rated for like -32°F up to like 400+°F I know it works well. Diver for light runs at like 85°F. Heater blows air that’s coming out at 160-180°F. Tent walls are a few less than the 75 I have it set to.
 
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