I just moved my girls from veg tent on 18-6 under an HLG 225 to my flower tent on 12-12 under a 600W HPS. I am trying to figure out if I have adequate ventilation to control temperature (flower tent is 14.25 sqft), but the HPS puts out a way different light than the LED and I don’t know if the light is affecting my temperature reading. Thermometer currently hanging from string at canopy level just wide of the light, but well withing its throw. It is reading 90f when HPS turned to 600W, and 80f when turned to 400W. Could the placement of the thermometer be artificially increasing my temp reading??? I really want to switch to 600W, but afraid of getting too hot!
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@WPPH4709 never used hps but know they are hotter. It sounds like your thermostat is placed in the proper position tho.
What type of housing do you have for the light? I run MH/HPS
Its a Vivosun air cooled hood.
I fight high temps in my set up. I place my temp gauge at the same level of my plants height.
I use an cloudline S6 to vent out the air from my air-cool hood, and it’s set high to keep the temp inline.
It sounds like you are running hot…you need to adjust your intake and exhaust…
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Ok. That was my initial thought too. My tent exhaust is separate from the light housing. The housing draws fresh basement air in, through the light, and out with a dedicated 6 inch inline fan. . . . BUT I used a Lowe’s in line booster fan. It says its 240 CFM, but is nowhere near as strong as my exhaust fan just based on feel. Currently using passive intake. I guess the best course is to move the crappy little Lowe’s fan to the intake port and put a real blower on the light hood . . . Sound about right?
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Also if you can cool the room the tent is in, it helps. I usually kept my house at 73 degrees, but run 71. My intake is close to one of my A/C exhaust fans.
You can also flip your flower stage to run lights at night.
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I can’t grab pics now, its dark time. But very similar setup. It’s in the basement. Ambient temp stays steady under 73. I run lights from 7p to 7a and all fans and ballasts are outside of the grow area (except the little circulation fans). I’m pretty sure its just the cheapo Lowe’s fan cooling the hood. I just wanted to check in to make sure it was a problem before I ordered another $100 part for the room. Was hoping I was just temping the space in the wrong spot. Sounds like its necessary though. I’ll update when fan gets here and upload pics. Thanks for the input man. Makes me feel better about dropping more coins!
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Luckily the ballast can be dialed back to 400W. I can use that to control the temp until the fan gets here. Though I should probably drop the light down. Glad I typed this. I would have forgot!
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I was able to get an ok pic of the setup. The little Lowes fan intakes on the left and discharges front right. Also able to get temp down by adding an additional fan blowing over top of the canopy directly at the extraction filter. Still probably going to install a larger fan on the light cooling side though. As I’m pulling so much air out of the room the humidity has dipped to under 50rh. Addition pic just for viewing pleasure! 
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