can someone explain how this works, i was under the impresion that i could stick my thermometre where my plants are about 5'' below my lights, but apparently not because it will mess up the reading??? read something about needing a digital thermometre to read it properly....will it be colder than my reading says and is radiant heat bad for the plant?
radiant heat
- Thread starter cookin
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LUDACRIS
New Member
put the thermometer in between the plants(shade from the light)and measure.
you want 74 day and 68 night.
this is measuring radiant temp.
Room temperature - Wikipedia, the free encyclopedia
this is ambient.
you want 74 day and 68 night.
this is measuring radiant temp.
Room temperature - Wikipedia, the free encyclopedia
this is ambient.
Infrared Thermometer - Infrared Thermometer made by Mannix - Dickson Supply's AccentShopping.Com 1-800-456-5267 if your talking about this kind of digital thermometer, it will tell you the surface temps of your plants or walls, etc. a regular thermometer will give you ambient or room temp that is for the entire area.
LUDACRIS
New Member
yes true but it depends on where you place the regular thermometer.
LUDACRIS
New Member
because you are going to get a sky high reading because of the RADIANT TEMP coming directly from the lamp beaming onto the thermo.if you have a basic thermometer just cover the sensor at the bottom with a piece of cardboard(shield it from the direct light) and you will get the radiant temp in between the plants and not from the light source beaming straight on to it.
cool i'm kind of getting it now, so if i want to know how close i can have my light it would be the reading in the shade, does the radiant heat that the top of the plant is getting not damage it though, or do you need to just use a bit of common sense and choose a height where the temp is good and it doesn't feel too hot at the top. reason i'm so bothered about this is i have a cool tube so i'm try to get it as close as possible
LUDACRIS
New Member
that's a perfect example.well explained.
Your plants are much more sensative to ambiant heat (the actual temperature of the air, in the immediate vacinity) than they are to radiant heat (the heat carried by the enrgy of the actual photons of light being radiated).
Radiant heat from the sun travels through the vacuum of space without even warming it up - but when it reaches us and hits the pavement in the street; the pavement becomes warm. As the pavement warms up, it releases heat into the "cooler" air; which makes the air "warmer" - this "Second Hand" heat is called ambiant heat.
Like NoDrama said, you can feel the warmth of the sun on your face, even if it's cold outside - that's radiant heat. The ambiant heat only rises as "things" get warmer during the day (from light radiation) and the air temperature stabilizes.
Anyway, the point is, don't worry too much about radiant heat - it's the ambiant heat you have to be careful of. That's why you place the sensor in the shade - to get the actual ambiant air temp! 85 or 90 degrees f., ambiant, is getting pretty warm! But 85 or 90 degrees f.,radiant, is just barely enough to make your hand feel warm. This is why we use both methods to keep the temperature under control - thermometer sensor (in the shade) for ambiant temps and "open hand" under the light for radiant temps! The radiant temperature can easily be 90 degrees f. (or higher) before it is hot enough to do damage to your plants or "feel too hot" on your hand.
Radiant heat from the sun travels through the vacuum of space without even warming it up - but when it reaches us and hits the pavement in the street; the pavement becomes warm. As the pavement warms up, it releases heat into the "cooler" air; which makes the air "warmer" - this "Second Hand" heat is called ambiant heat.
Like NoDrama said, you can feel the warmth of the sun on your face, even if it's cold outside - that's radiant heat. The ambiant heat only rises as "things" get warmer during the day (from light radiation) and the air temperature stabilizes.
Anyway, the point is, don't worry too much about radiant heat - it's the ambiant heat you have to be careful of. That's why you place the sensor in the shade - to get the actual ambiant air temp! 85 or 90 degrees f., ambiant, is getting pretty warm! But 85 or 90 degrees f.,radiant, is just barely enough to make your hand feel warm. This is why we use both methods to keep the temperature under control - thermometer sensor (in the shade) for ambiant temps and "open hand" under the light for radiant temps! The radiant temperature can easily be 90 degrees f. (or higher) before it is hot enough to do damage to your plants or "feel too hot" on your hand.
LUDACRIS
New Member
bigmeister
Active Member
I have some sprouts that are just getting their third set of leaves (White Rhino, El Nino, Sensi Star,Lemon Skunk,, Afgan Kush, Himalaya Gold, Cheese, Big Bang, Belladonna, Alaskan Ice under four T-5 bulbs.
I am growing in rockwool, daytime temperature 76-78 at plant level (at level of plant- not in shade), humidity 55% with good circulation from fan.What is the optimum height to have the T 5's from the top of sprouts at this age?
How close can I be to get maximum growth if I maintain the 76-78 temperature?
I am growing in rockwool, daytime temperature 76-78 at plant level (at level of plant- not in shade), humidity 55% with good circulation from fan.What is the optimum height to have the T 5's from the top of sprouts at this age?
How close can I be to get maximum growth if I maintain the 76-78 temperature?
It really depends on what your ventilation system is doing. But I would guess about 3"(+ or -). Drop your lights down and give it the old "Hand Test" at canopy level. On your bare skin, you should just feel "a little warmth" - not like "there is a heat source near my hand!". It's the difference between "comfortably warm" and "over heated".