Throw out that thermometer...?
- Thread starter Kingrow1
- Start date
cogitech
Well-Known Member
Sure. As long as the fan is providing a gentle, horizontal breeze at the bottom 1/3 or 1/2 of the tent, the ambient temperature recorded by a shaded thermometer in this area will accurately represent the temperature of the air that the plants are living in. Far more accurate than a thermometer placed above the light(s), that is for certain.
coreywebster
Well-Known Member
Above the light line and above the light are different things.
Must not be in direct light.
Must be in well mixed air.
That's as much as we can do.
Must not be in direct light.
Must be in well mixed air.
That's as much as we can do.
It definitely does vary.
Personally i hang three thermometers.
One at the bottom, of the tent, under the canopy. Attached to my thermostat controlling ambient temperature.
A second thermometer at the main canopy.
A third at top canopy, under the light.
Temps always read something like this when lights are on-
Top canopy - 26 - 28'C
Main canopy - 24'C
Below canopy - 21'C
The infra red light / radiation, from the grow lights, is whats causing the extra heat.
Fans dont affect this heat at all.
They dont even blow it around.
I figure we cant blow light we see, around with a fan. I dont believe infrared light is any different.
Besides heat always rising.
Personally i hang three thermometers.
One at the bottom, of the tent, under the canopy. Attached to my thermostat controlling ambient temperature.
A second thermometer at the main canopy.
A third at top canopy, under the light.
Temps always read something like this when lights are on-
Top canopy - 26 - 28'C
Main canopy - 24'C
Below canopy - 21'C
The infra red light / radiation, from the grow lights, is whats causing the extra heat.
Fans dont affect this heat at all.
They dont even blow it around.
I figure we cant blow light we see, around with a fan. I dont believe infrared light is any different.
Besides heat always rising.
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OldMedUser
Well-Known Member
I don't know about the rest of you guys but I have a 16" fan mounted on the ceiling blowing air across the canopy at an angle that creates a circular air flow around the room, 9x7x6.5'h. And a 12" oscillating fan on the floor waving back and forth in front of the bases of the plants so my air temp is the same from floor to ceiling. I also use a laser thermometer to see how warm the top leaves get under the light as I like to run it fairly close. Like 12 - 18" with an open 1000W HID.
Even a small circulation fan in something like a 4x4 tent will stir the air up so there isn't going to be a lot of difference except for where the air comes in at the bottom.
Even a small circulation fan in something like a 4x4 tent will stir the air up so there isn't going to be a lot of difference except for where the air comes in at the bottom.
cogitech
Well-Known Member
The only logical conclusion to be drawn from the responses (including my own) is that every single grow cabinet/tent/room is completely unique and there are no absolute answers to the original question posed. There are simply too many variables to compare one to the next.
All I know is what works in my tent, works. Not throwing my thermometers away.
All I know is what works in my tent, works. Not throwing my thermometers away.
Thats right. 100%I don't know about the rest of you guys but I have a 16" fan mounted on the ceiling blowing air across the canopy at an angle that creates a circular air flow around the room, 9x7x6.5'h. And a 12" oscillating fan on the floor waving back and forth in front of the bases of the plants so my air temp is the same from floor to ceiling. I also use a laser thermometer to see how warm the top leaves get under the light as I like to run it fairly close. Like 12 - 18" with an open 1000W HID.
Even a small circulation fan in something like a 4x4 tent will stir the air up so there isn't going to be a lot of difference except for where the air comes in at the bottom.
Personally i run passive extraction.
My air intake comes from the bottom of my 4x4.
8inch inline, extraction fan sits ontop outside the tent blowing all the air straight out.
Ambient temperature can only be as good, as the intake air, and the room, the tent is in. Without resorting to air-con.
Ive found for myself, oscillating fans do zilch, to abient temperature. Besides just blowing air around the room.
Personally. If my tent is the same temperature, top to bottom, the fix has been extra extraction.
The heat from infrared is very real.
Its the same heat hitting our hand, when we place it under our lights.
Its infrared light.
Light cannot be physically moved. It can be reflected though.
This light is being reflected off the tent. As well as bouncing off the plants. Usually bounces straight back to the top.
If there is adequate extraction. The canopy shades, and insulates the cooler intake temperatures extremely well.
I like extraction, more than i like oscillation.
Its fresher air too.
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ANC
Well-Known Member
Unless you have climate control and super insulation, grows change from month to month due to the seasons.
This is why notes can be so helpful when you get something right. You try the same thing 3 months later and it backfires...
meangreengrowinmachine
Well-Known Member
I think this is so far the most accurate measure of temp in this postIt definitely does vary.
Personally i hang three thermometers.
One at the bottom, of the tent, under the canopy. Attached to my thermostat controlling ambient temperature.
A second thermometer at the main canopy.
A third at top canopy, under the light.
Temps always read something like this when lights are on-
Top canopy - 26 - 28'C
Main canopy - 24'C
Below canopy - 21'C
The infra red light / radiation, from the grow lights, is whats causing the extra heat.
Fans dont affect this heat at all.
They dont even blow it around.
I figure we cant blow light we see, around with a fan. I dont believe infrared light is any different.
Besides heat always rising.
It's as technical as you want to make it, but the reality is that different points in the tent will register different temps depending on convection currents, air flow, dead air, and so on.Reading replies leaves me in good company, growing in tents is vastly more technical than at first thought, most of you have this down but i will add that wind in tents is un-natural to growth, air exchange is enough.
I'm slowly going through these principles again
We also like to think that things MUST be at an "ideal" temperature, humidity, etc, but forget how wide the range of parameters our little plants can be happy in provided you get things like airflow right. As you say, we don't want "wind" but we need enough air movement which is why we use supplementary fans to stir the air around. The higher the temps, the better airflow needed because of humidity in an enclosed space.
You don't need to overthink some things, and by Christ I'm guilty of overthinking at the best of times, as they say "If it ain't broke, don't fix it", you'll only end up being like me and overcomplicate things for no apparent or rational reason...
tyke1973
Well-Known Member
Ain't used one in years. Same with ph pen ,No need .Just go on how the plants look ,if they look good and it's warm ,they will be ok .Just makes you do things ,that cause more damage than good .You know if it's really hot ,and the temp need sorting ,but even then if the plants look happy leave em .
Lol.
I reckon all green thumbs are weirdos.
You and i might be like chalk n cheese.
I havnt used a dehumidifier, or humidifier ever. Never needed them.
I dont even have a hygrometer to check.
But i like having a thermostat, connected to my heater for ambients.
And use a reptile tank thermometer. With two ends. So i can have 1 at top canopy, and 1 at main canopy.
I check my local weather, to see the humidity for the day.
Chalk n cheese.
Funny man
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Kingrow1
Well-Known Member
No each tent uses the same scientific and physical principles and thus forth exact things can be determined, variables are what i deal with here and i personally hate this 'every tent is different' and its certainly not how i grow.
Kingrow1
Well-Known Member
You measure a gradient not the air temp as it rushes through your tent, even more inaccurate using multiple thermometers if they all give different temps, one would assume each is affected by different external heat sources and not simply the air which should be reasonably similar all over if measurements are accurate as per my ruck 400cfm fan which does not leave any still air patches anywhere in my tent.
Kingrow1
Well-Known Member
So after years of growing and studying all these little factors i'm the same as you, read plants ignore all else and trust in your skills