hey first grow in a 2x2x2 growbox. i currently have 6 42 watt daylight cfls and 2 23 watt 2700k cfls on 4 LST'ed bagseed babies about 3 weeks into veg. using a AC 120V dayton 100 cfm fan for exhaust and a AC 120V tubeaxial 40 cfm for intake. i didn't think i would have this problem using cfls (the ballasts get very hot) but the temps in the box began to high when i put the carbon filters on and i ended up halting growth for like a week. took them off but still cant get the temps down below 90 without the door open and a large fan blowing fresh air right in. should i add another exhuast fan or intake or both? it already takes a large oscillating fan to cool the box down would a small wall mounted one inside do anything for the temps(besides promoting strong stems)? most importantly, would using a150 or 170 watt hps instead of eight cfl bulbs with eight heat producing ballasts(within the box) reduce heat? or is a 2x2x2 space much too small for HID lighting? appreciate any response thanks
Hey, I'm doing a cfl grow in a space even smaller than yours. I don't have a link, but if you look in the Indoor Grow Journals section, or search my recent posts, you'll find it. I had the same problem, and I'm using 315 total watts compared to your 252. I'd say use only passive cool air intake (no fan). You don't want any turbulence in the box. Turbulence caused by an intake fan can screw up the natural process of heat rising. Use any and all fans as heat exhaust the very top of the box. Especially because you said the carbon filters are causing the problem. Just make all fans exhaust. Worked for me. PS I don't think air flow does much to promote strong stems, it's a bit of a myth, so don't worry. Weak stems are mostly from inadequate light.
thanks dude very useful. how many intakes do you have on your box? i guess you cant then put a carbon scrubber on the passive intakes right?
As another CFL user, I too have had that problem. I wound up adding another exhaust port about halfway up the box along with one near the top. I increased my fan size on my intake to bring in fresh, cooler air, and used two smaller fans for the exhaust. It seemed to help mine. I would also suggest that you keep your intake so the plants can get fresh air.
Not if your exhaust is strong enough to create something called negative pressure. Basically the exhaust fan will cause air to constantly be sucking in through the passive intake. I vote for using an intake fan. I use 1 intake fan and 2 exhaust fans in a very similar set up. Temps are perfect.