High temps- questions for you guys

[rr14]

Hi guys. I have a temp sensor mounted on my screen in my scrog setup. I have a 600 hps (6" air cooled) with an 8" vortex fan hooked up. I"m currently seeing 90-91* on the screen with the following:
-1 small fan shooting at the bottom of the net from the floor
-1 6" oscilating fan
-1 6 fan on low drawing cool air in at approx 30-50 cfm
-air cooled hood is drawing air approx 65-70* through the hood

When I feel at the top of the net, there is good airflow. The hood is definately getting a great amount of 70* air across it. The net is 14" from the glass on the hood. The room is 10' by 5' by 8 foot tall. This is the only light in the room. BTW, temps without the air cooling on for the hood were about 100* after an hour or two. I'm currently not running co2 but will be in about 2 weeks. Plant is in it's first week of flower. It is a 2 by 3' scrog.

My questions are:
1. what temps are you guys seeing?
2. it seems like I've done enough to fight radiant heat. what are your setups?
3. Should I be worried about this?

 

[NorCal]

those temps seem pretty high for just that light, if it wasnt aircooled maybe but with what you got it sounds weird, maybe some hot air is leaking out like from your a/c lights? if you see my post im rnning 1000 and 600 watts in a 3x5x8 and with only a 4" fan for the hoods and my temps dont go over 86 as thats what i have it set to. some peeps say after 90 deg, lots of your plant functions cease.
i just dont see how those temps are occurring in such an area????

 

[Guest]

Yea thats odd for such a large space,90 is definately not good to flower in without co2 enrichment,your on the border line for veg.75 degrees may be optimum veg temp,but I dont even turn on the AC unless the top fans read 85 degrees on a lazer thermometer.A cool mist humdifier besides being a great natural mite repellent is great for the plants when vegging at higher temps.They cost about 30 bucks get one with a visable mist.

 

[rr14]

I feel a ton of heat radiating off the top of the hood but the rest of the room is in the low 80's I'd guess. I'm going to hook up another thermometer in there. I do have a fan circulating air from the cool side of the room. It doesn't feel like the air leaks on my hood air really that great. There's just leaks at the corner of the hood where the glass mates up with the hood.

I took a look at the plant and it was a bit stressed with a few droopy leaves. I moved the light up about 4 more inches to about 16"-18" off the plant. I also moved a fan to blow directly between the plant and the glass on the hood. It's aimed just slightly high enough to not shake up the plants much. Temps are back down to the mid 80's from around 90-92.

 

[rr14]

Oh yeah, I'm going to hook up the scrubber tonight so that should help slightly.

 

[Guest]

Not as much as a cool mist humidifer would help them.Plants thrive during veg at 70% RH if you can get it that high,not so easy to do.Anywhere between 60 and 70%RH and you'll be ducky at 85 plus degree temps

 

[NorCal]

maybe the 8" fan is throwing hot air back into your room? if not get a beefy exhaust and place the duct right around the top of the light...

 

[Guest]

I think one key piece is -air cooled hood is drawing air approx 65-70* through the hood

Are you saying the air going through the hood is 70F but the temp on your screen is in the 90's? If I'm reading that right I'd suggest experiment with placement of your temp sensor. I doubt the actual screen would heat up and thus raise the sensor, but it's possible if you're seeing that large of a shift in temps from the hood to the screen. Just seems weird.

 

[SEEDYNONO]

is the sensor getting direct light?

i think intense light focused on the sensors will cause them to show a higher reading than the actual temp?

 

[Formaldehyde]

Isn't 600W a little overkill for a 2'x3' space? That's 100w/sqft. Maybe that's why...

 

[NorCal]

2x3? afaik he said its 10x5x8

 

[Kush King]

nah u just need to have the place yuor drawing the air from, in a diffrent room or outside. becuase the exaust is prolby makeing the iar hot over time there for just hot air is running threw the hood.

maybe cuz your space is so small try sucking from the bottom.

 

[Ono Nadagin]

he said the room was that large and the scrog was 2'x3'

 

[KillerDemo]

bump

 

[rr14]

correct. the room is that big and the scrog is 2 by 3 feet. Currently the light is about 16" or so from the screen. Temps are in the low 80's but the light has only been on for an hour and a half. The air is coming from outside and getting vented back outside. The air temp outside the room is in the 60's to 70's.

The humidifier sounds like a great idea. My humidity currently is at 39% in both the veg and flower sections.

 

[Guest]

Its only about 30 dollars,and can make a big difference in vegging plants.With humidity that low I'd run it during lights on in veg always,it will help a lot.Thats too low for veg,fine for flower though.Just make sure the one you choose has a visable mist,some dont and wont do much good.Vegging plants love em,spidermites hate um,thats good enough for me.

 

[Equipment Junki]

The 8" Vortex is rated at 747 CFM.

That ought to be plenty for one 600W HPS. Basic rule of thumb is 6 - 8 watts per cfm.

What are you reading temperature with a recording thermometer?

This is all fine and well, but if you get a lazer thermometer (about $70 at NAPA autoparts) take canopy readings all around. Put the lazer right up to the leaves.

I like to shoot for right around 86 degrees F.

I am testing Sunlights Equalizer light diffusers right now, with about 18" of distance between the arc tube and the top of the canopy, and we're 1 week in to 12/12.

P.L deep hoods with Equalizer diffusers.

Will take some pics and report at week 6.

Respect

 

[Equipment Junki]

Also, you guys check out VPD which stands for Vapor Pressure Deficit.

What we've found out is it isn't PAR watts that matter, it is PUR (Photosynthetic USABLE Radiation) which is tied to the VPD.

Might have found a use for that fogger...Will run test next round at Skunkworks.


Respect

 

[rr14]

man, I can't imagine how guys are getting their setups to work in closets. My temps are still at about 82-84 with the hood 16-18" above the grow and with it air cooled. I have fans focused on the glass to cool that too.

 

[riverrat]

You might try to insulate the top of the light hood and all your ducts leading in and out. This should lower your temps a bit.