When measuring temps for your room is it the room temp in general or the temp under the lights that you are concerned with?
And therein lies my conundrum. Everything I read says to keep the "room" at a certain temp. Well, my plants are growing under the light and so are experiencing that temp really, not room temp. Either that or I am missing something really basic. I want to end up with nice and tight, not loose and airy!
Check the temperature at the plant level but shade your thermometer from the light .I allways used a oscillating fan to keep the air moving around my cabinet.-Bud
This is my setup. I have a 1k mh light, two oscillating fans, one for the ballast and another for the plants. I have a 6 inch 270 cfm inline fan pulling outside air through the light in addition to a 6 inch scrubber. Light and scrubber are exhausted to the attic. I also have an 8 inch 500 cfm fan pulling in outside air and dumping it directly into the room. I think I am just missing something simple but I don't know what. /monthly_2010_10/r2.jpg.664c903e29003ebc900624bc1d460b5f.jpg /monthly_2010_10/r3.jpg.9c582678a5ebf890d975681fa22db7df.jpg
With proper air movement and that vented reflector you should easily be able to achieve optimum temps, unless you live on the equator and don't have air conditioning. What are your ambient temps outside the room where you are pulling your air in from? In my setup I have a 1k watt HPS w/vented reflector and I am pulling air from inside my house (ambient temp of about 70 degrees) through the reflector using a 6" 435 CFM inline fan and exhausting under my house. My temps are never more than 10 degrees warmer than the house ambient temp directly under the light. I can easily maintain under 80 degrees except in the heat of summer when the inside house temps are higher.
The air that is going through the light is coming from a vent in the attic. That duct sits next to one of those screens that you see on the side of your house and is probably a mix of attic air and outside air, I have not measured the temp but I'd say it is probably 60 to 70 degrees. Before I hooked up the inline fan to the light the temp under the light was 95 degrees, now with the inline fan hooked to the light the temp under the light is 88 degrees. The room temp itself, taken away from the light, is 80 degrees. I just don't want to end up with heat stressed buds and have them turn out all light and airy, I'm shooting for nice and tight. It is my understanding that high temps lead to light and airy unless additional co2 is introduced to the room. The only co2 introduction to my room is the outside air being pulled in from the 8 inch 500 cfm fan that gets dumped directly into the room.
Yes it is true that high heat can affect the density of buds, however in my experience it is 90% dependent on the genetics and only 10% dependent on fluctuations in environmental conditions. Unless you are talking about extreme heat over 90 degrees. 88 is a little warm but you can still grow good buds at those temps. I would say drawing air from the attic would not be ideal, attics are musty, and dusty as well as exposed to high temperature fluctuations. Increase the CFM rating on your exhaust fan and by pulling more air over the light you may be able to further decrease the temps directly under the light. No matter what you do you will always have a "Hot Spot" directly under the light. Constant air movement blowing across that "Hot Spot" will also help to disperse the heat throughout the room. My Hot Spot usually runs about 3-5 degrees warmer than the ambient room temp, but as long as your Hot Spot isn't hitting in the 90's and your room temps are in check you should be fine.
Where is your ballast located and is it digital or magnetic?? You have plenty of air movement through the light to cool it so I feel like there's another variable at work.
Yep, you're not kidding about the attic not being the ideal place to get air from. The room does have a funny smell to it. Unfortunately it's the only option I have. I think that now that it is the fall and will be much colder when I flip the light in November that the temps will be ok. I just like to do things right when I do them and stress needlessly when I can't and don't have control over the process or have to do things other than what would be the ideal way to do them. My plants are 2 weeks old and have already shown signs of heat stress until I got the inline fan put in. I agree about increasing the cfm of the inline fan, but, my take is that by the time I flip the light the air coming in will be much cooler. Then I get to stress about having my light explode due to moisture and heat related problems. LOL!!! Ain't life grand!!!
The ballast is magnetic and is in the room. I should have the ballast in another room, I know that would go along way towards solving my heat issue, but It has to stay in the room. I do have a small fan blowing on it when the light is on. Before I put that fan there you could hardly touch it, now it's really cool to the touch but that heat is getting dissipated to the room.
Why not draw your intake air from inside the house and not the attic? You get a more controlled environment that way. It should be easier to maintain even temps that way. I just use a passive intake that allows air from inside my hallway outside my growroom to cool the light as well as provide fresh air to the plants.
It's for stealth reasons. I don't need people coming over and asking me " hey, what's that hole, grill, duct, etc... for". Also, the location of the room in the house prevents me from using a closet or some such. there is one place I could use but, alas, the wife would kill me!
When you are working with less than optimum conditions you have the chance to achieve less than optimum results. I think you will be okay with those temps though. I would recommend that you try and filter that intake air coming from the attic.
I had a feeling that was the case and therein lies your heat issue. Until the ballast is moved your heat will remain higher than expected for a given airflow. Get imaginative man. Put the ballast in the attic and run the cords along side your ducting for example. Imagination and ingenuity are much cheaper and easier than upping CFM.
Good Idea. :thumbs-up: Now that's using your noodle! That's why you're my hero! :flyy: Not that you need it!
I agree that the ballast should not be in the room, however, there is no way i am putting it in the attic. I can't put it anywhere but the room so i guess I just need to get a bigger fan inline. Thanks for everyones help!
Just set yer thermometer right on the grow table where the plants are. The temp where the plants are is the only temp that matters. In my grow space (the garage), it may be 70 in the room, but under the light is 83 or so. In the summer it can really get UP there. Dixie
I am actually looking into that now. I will be building a veg room in the garage in about a month. Any good suggestions for digital stuff?
