Most grow guides recommend cooling lights with air taken from outside the grow rooms, using a separate fan and charcoal filtered system to handle air exchange. I've always tried to save money and use one fan for both, and have largely succeeded. It hasn't been a complete success, however, and I have always had problems that I think are made worse by NOT running separate systems for light cooling and room air exchange. For example, tonight I noticed some issues near the tops of my plants closest to the cool tube. When I cup my hand around the top bud, the light feels pretty darn hot on the back of my hand, so I know the bud is getting toasted. I can't move the light up and I don't want to bend the stalk down just yet because of crowding issues. I notice the fan leaves up highest in the whole room are starting to look like a taco, folded down the spine of the leaf. The edges are folding up and a cross section of the leaf looks like a V . Also, outside it's been getting colder and drier, and my RH has been below 30% in the veg room and below 40% in the flower room. While that is good for mold control now and again, I like to keep the bloom room between 45-55% RH, and 50-65% RH for the veg room. The temps in both rooms are dropping. It's 69 in the veg room and 73 in the flower room. What to do? What I should do is crank UP the light cooling system and make that more efficient by cooling with the coolest air possible (not the hot air from inside the grow room but the cooler air outside the room) , and turn down the air exchange. Why? Because by turning down the air exchange you are making your room less of a wind tunnel. To keep your plants healthy in both veg and flower, you only need to completely replace the air in your rooms once at least every hour or so. The air outside the rooms is dry and cold, so slowing down the air exchange will help you keep the rooms warmer and wetter. I should add a humidifier, and that should do it. I have had this issue in the past, as I imagine every grower in the Northeast has. If I had separate light cooling and air exchange systems, I could slow down the air exchange to help keep the RH up in the rooms without increasing the heat at the tops of my plants. Do you guys/gals run separate air exchange systems and light cooling systems, or do you combine the two functions? If you don't run separate systems and have fluctuations in the ambient temp outside, what do you do?
I run a 8inch, a 6inch and another 6inch....all with HUGE filters to cool off 2-1k lights and 3-600s....but I hang them vertically
You just need to remove the hot air coming off the lights at a decent (or nominal) rate. The faster you remove it the lower the temp at the top of the plants will be. (Of course, this also depends on ambient air temp. ie. If you're trying to remove +120 deg air mass from bulb you can remove it easier if ambient air is 75 than if it were 85. Simple thermodynamics.) Then you can position plants below the lights to your liking. MH are very hot. I have a cheap 10" fan (at high speed) placed under a 400W MH bulb and I can easily get plants 12"-14" from the light and the tops at room temperature.Just a diagram I thought I'd throw in with respect to hood design and light intensity - /monthly_2013_11/light-Canopy.jpg.fd290dbbd2a943fd90ef2dd6dd890393.jpg
Thanks for the reference pic, Ifsix. I am pretty much set up now, except I will add 2 more cool tubes in the same 6" lines, between the existing tubes and the plenum. This will give me a total of 2400 W for approx a 6'X5' space. :new_blackey: After much research and considering, and a little experimentation, I have come to the conclusion that vertical lighting is good if you have larger spaces, but when trying to cram lots of HID watts in a small space, you need hoods and cooling. I now have two ventilation systems: one for air exchange for the grow rooms, and one to cool the lights. For the air exchange system, I have two carbon filters, one in each grow room. The one in the veg room will pull a little less than the bloom room, but that's OK. These filters are tied to a 6" can fan that is just running in the plenum for noise reduction. It vents into an 8" flex duct that runs to the outside of the house. The air coming into the rooms goes into the workspace first, then into each of the growing rooms via passive,filtered, lightproof floor level intake vents. The output of this system is 6" (423 CFM fan) and the intakes are collectively the equivalent to two 10" round ducts. I have this fan on a speed controller. The cubic feet of the grow rooms totals about 450. Assuming approximately 30-50% efficiency of the fan, at max speed I can prob exchange the air in the rooms every 3-4 minutes. :happy6: The light cooling system takes air from the floor of the basement where it is coldest and brings it into the rooms via an 8" rigid duct line. The plenum is powered by an 8" can fan venting into a straight rigid 8" duct direct to outside the house. No turns in that. The lights are all ducted to the plenum and draw air from T's in the 8" intake duct.
Ahhh from my elec panel, lol.. Nice setup FF....don't worry man, pretty soon that room will grow into a 10x10 room...then youll do something even crazier!
Sweet set up FF ... You guys make me drool with all the space you have.... I will Lu e vicariously through you....
