# 80 degrees in the grow room...



## LassChance (May 7, 2009)

Happy to announce the arrival of a bouncing 600w HPS.  Hung it last night in the temporary grow space (garage) where it's MUCH cooler because it's underground...and to my surprise, the thermometer on the grow table read 80.  huh.  The rest of the room is quite cool.  I have a fan blowing above the plants and under the light...but 80 degrees is 80 degrees.  I dont know what to do to lower the temp...I dont even have my reflective"box" built yet, so the planrts are right in the big open garage. What to do?  What will the effect of 80 degrees be on my babies?  and once I build my 5X5 box-without-a-top how HOT will it be in there, THEN???  The hummidity is 52.  When I hold my hand at the height of the plants it doesnt feel hot...and the light is 20 inches above their heads.

New digital thermometer.

How bad is this?

Kass


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## NYC_Diesel x Jack_Herer (May 7, 2009)

Is the thermometer getting direct light?  I have found that putting them in direct light raises the reading.  Try leaving it the same distance but placing it in shade.  Either way, if 76 is ideal you aren't going to cause any harm by having them at 80


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## ArtVandolay (May 7, 2009)

Take the actual temp in the garage away from the light.  I keep track of my lighting temp issues as a spread over the ambient temp (example surrounding air temp 70, grow box temp +20).  By the way, that's pretty much the actual situation with my dual 150 watt HPS in The Hemp Goddess DIY cool tube with 138cfm fan pulling air through it and exhausting outside the grow space.

You're going to need a cool tube or a sealed vented hood for your light, I predict .  It will also help to relocate your ballast away from the box as well, if you haven't already.


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## BuddyLuv (May 7, 2009)

Art pretty much sums it up, air cool the hood,


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## Lemmongrass (May 7, 2009)

shouldn't you put you probe in direct light because the top of the plants are likewise in direct light? 

mien is black so it may hold more heat. ive never been sure about this.


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## pcduck (May 7, 2009)

Temperature readings should been done in the shade.
Just put a piece of cardboard over your thermometer


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## Lemmongrass (May 7, 2009)

Thank you. why is this tho? my plants are certainly not in the shade :]


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## crozar (May 8, 2009)

Damn! i couldnt sleep all night because of this , i dint kknow that light increase the readings , OMG! , i got paranoid ., so my temperature is basically lower! 
i need a cooltube now lol


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## PencilHead (May 8, 2009)

Heat is transfered in 3 ways: convection, radiation and conduction.  When your thermo is laying in the light, it's not only reading the convected and conducted heat, it's also reading radiated heat. Lay something dark like a black framing square in the sun for a bit and you could fry eggs on it. Your plants absorb and disperse the heat by the way they are built.  Your thermo isn't.  Put it in the shade for best results.  Un-huh--ask ME what time it is, I tell you how to build a watch.

IMO 80 isn't too bad right at your plants.  77 is better, but 80 isn't 92.  What Art said about ambient temp is a biggy.  If you can get enough ventilation going, you'll balance out those cool areas in your garage with the hot areas.


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## pcduck (May 8, 2009)

Thanks *PencilHead* I am way too :stoned: to spell all those big words:rofl: I could think it but not write it:rofl: Great analogy:aok:


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## Lemmongrass (May 8, 2009)

thanks ph, i still dont get why the plants wouldn't also catch the radiation as well tho. but im sure there is a huge absorption diff between a shiny green lef and a dull black probe!

so if the exposed prob at the top of my plant reads 80-90, but under a couple leaves it is 73-82 i should roll with the lower one. room feels like 90 tho >.< i have a shitty home depot fan sucking air form the household AC and it still stays at 82. time to buy a hundred dollar fan i guess.


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## Larnek (May 9, 2009)

You'll need something if its staying hotter than 90 all the time, but my last grow was in in the high 80s low 90s almost the whole time and you can see my gain from it. Didn't have a problem with my Citral, but of course every strain takes heat a little different.


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## NYC_Diesel x Jack_Herer (May 9, 2009)

The other consideration is that the plants are breathing, the thermometer isn't.  You can see what I mean by doing the following experiement.  Take two identical cuttings from any leafy plant and immediately stick them both in glasses of water filled to the same point, except place a fan in front of one.  Come back in an hour and you will find the plant with the fan on it has drank more water.  The reason for this is becasue the moving air causes the plant to be able to...for lack of a simpler description....breathe faster.

Pretty cool trick, learned that one in botany.  Anyway the point is that the plant is breathing, it is not a sealed container like a thermometer.  The difference is equivelent to standing on your driveway on a sunn yday versus sitting in your car with the windows rolled up on a sunny day.


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## Lemmongrass (May 9, 2009)

HA! thats the process i was missing to make it make since! thanks dude lol.


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## Budders Keeper (May 9, 2009)

Hello LassChance, if I understand correctly you will have a no-top-box, 5X5, inside your garage. I have not heard anything mentioned about venting the garage. If your not pumping air out or in the garage you will probably have humidity slowly build till it gets up to about 70-80%...I did. 
  As far as temps, unless you have a sensitive strain 80 degrees will be fine...but...just looking into the future...a dehumidifier with bump those temps up further which may present a problem for you. I also have a 5X5 room in my garage but it is enclosed. I run 2-400's in it and my biggest battle is humidity. Outside temps where I'm at run 75-95 all summer and my temps stay 78-80 only because I run my lights at night and leave back garage door open whenever I can.


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