Hey everyone, I know this question has been over-asked, but I figured I'd ask the question again using the specifics of my box. So the dimensions inside my box are 22'' H, 13'' L, and 10'' W. I have 3 24w T5 bulbs which bring the temps in the mid 90's, I want to put some CFL's in there as well, but one 45w CFL brought the temp to 105. I want to put 4 CFL's in the box if I can, but I don't want my box to be a small oven, and I'm sure my girls would prefer they didn't cook in the box as well. I have an intake fan and outtake fan in the box, but they don't seem to be working as well as the fans in my smaller veg box, which is running with 4 25w CFL's and stays in the mid 80's. So what can I do without buying more PC fans and cutting more holes in the box? Should I just add a more powerful intake and outtake fan? Is there any aftermarket cooling system that I could plug into the power strip and hang somewhere that would cool the box down? *Also the ac is constantly running in my apartment, we like it cold, in the mid to high 60's, the box is in my closet but the closet door stays open, when my other veg box was in there it kept cool, this one doesn't for whatever reason. Thanks for the help!
First start by completely removing the intake fan. Passive intake is way better, and your intake fan is probably part of the problem. Other than that you may want to think about removing a bulb, box is pretty small.
So remove the intake fan and just leave the square cut as my passive intake? Or should I cut some small holes in the box for passive intakes as well? The only thing that worries me is smell during flowering. Will it be a significant difference? I have an ozone generator, would that keep the smell at bay?
I don't see how it's possible to say that 'passive intake' is 'way better'. I can't think of any circumstances where a passive intake would be 'better', ever. Only situations where it's not necessary to have a fanned intake. Care to explain?
I would use both fans as exhaust and make passive intake. You could also try and put a small fan in the box to cool the lights.
When temperatures are that high....decreasing the temperatures going into the box should be very cold... And removing lighting may be another last option.. Fans just blow around hot air. A/C cools
Yeah, thats exactly why you should have it in a cool room. Window A/Cs can start at about $99 and can cool up to 100-150 square feet of space. You can even put the box in your room and enjoy cool ambient air and have your plants enjoy it too
Whats the humidity in your box? I use a 1000w HPS light in a 23 1/2" X 18 1/2" X 72" closet. I have an exhaust fan, 2 intake fans, and I keep the temp around 84 degrees F at 28% humidity, and my plant is doing great. I've found that attaching exhausts directly to the light, or around the light, significantly reduces the heat thats generated. Having passive intake hasn't been a very solid idea in my past endeavors, mainly because I couldn't get enough air flowing in order to cool it all down. Its a fine line between too much and not enough, however. Just experiment, use objects to raise the humidity. Using towels that are wet with cold water and just hanging in your grow space can raise your humidity by as much as 20% and lower the temp by almost 30 degrees. Before i had done anything with the air flow, i did everything in my power to adjust my humidity, and now it stays at a constant both when the lights are on and drops to a constant when the lights are off. Good luck to you, and come check out my grow
Thanks for the help and suggestions everyone. This is a stealth grow, so the cab is in my closet with the door open, so it gets decent airflow. I keep my apartment pretty cold, the room where the cabinet is in runs about 67-69 during the day and with the windows open and ac turned off at night it gets to about 63-67. Now the closet in that room where the cabinet sits gets around 72-74 in the day, and probably 68-70 at night. The box fits three two gallon pots, and in about two weeks I'll have my girls in there (seedlings now). I need as much light as I can get, and the three T5's give off 2,000 lumens each. I def don't have what is recommended, so I'm trying to add more light, but keep it cool. So I guess what I should do after reading everyones suggestions is, do passive intake, switch both fans to exhaust, and try to put a fan inside the box to circulate and give off oxygen to the plants? Anything else? Am I missing anything? Thanks again!
again, watch the humidity, it plays a pretty big role in the growth of the plant. Get a thermometer that doubles as a hygrometer (humidity meter). They can be acquired from walmart for about $5. or with a five finger discount. Whatever's necessary. If you raise the humidity, you'll have a lot easier time controlling the heat within your box. Your set up is almost identical to mine it sounds, except i'm using a 1000w HPS lulz
My understanding of passive intake is that there is no mechanical assistance used in bringing air INTO a grow box (please correct me if I'm mistaken.) Exhaust is, in my own words, all the air that is expelled by whatever means. I use an exhaust fan in the roof of my grow room.
Sorry should have explained it more. And this is just my opinion, but in small grow boxes such as his, you can easy achieve great airflow with just a couple of exhausts and a passive intake. I'm not an expert, but I think in small boxes such as this, the intake fan creates issues with the air flow, such as circulating hot air throughout the entire case making it much more difficult for the fans to exhaust efficiently. Instead of having a temp gradient inside the case, say at the bottom temp is 70, middle at 75, upper at 80; your temps achieve an equilibrium in that your whole case is at 78. This is just an example not real numbers, and I have no proof, just my opinion. Think of it this way, instead of cool air being drawn into thru the bottom and filling the lower portion of the case; the cool air is being "shot in" hits the back wall and goes everywhere, including possible right to the exhausts where it gets shot right out the case. It never has a chance to cool the ambient air in the box. In larger grows, yes you will be more likely to need intake fans. Smaller grows, I think they cause more issues than they fix. Plus if you take a look at eniN6's grow thread, he has the exact same case as me, only our fan differ, room temps are similar, he runs in the mid to upper 80's, i run rock solid at 73. I should have phrased it differently, cause one way isn't the only way. Just my thinking on the matter.
I can't really comment too much on smell, I'm growing NL which doesn't have a really strong odor. I bought flat carbon filter sheets from amazon, cut them to size and "sandwiched them between my case and the fan. It works well for me and offers decent light filtering. Just keep in mind, a filter will reduce the airflow from the PC fan so you will have to compensate for that.
I love passive air intake. I can see the fan being an issue as well. The fan motor itself generates a fair amount of heat which you are passing air thru into your box. Passive air intake (best controlled and properly filtered for bugs/dust) is easy to achieve at a good balance. What you want to avoid is situations with crap loads of over pressure or negative pressure in the box. Some negative pressure is almost unavoidable unless you want to blow open the door of your cabinet. The math to calculate how many square inches of intake space (hole size) you will need to allow enough air to pass is fairly straight forward and depends on your fan's CFM rating. Back draft dampers and screens are easy to attach to ventilation holes. One good inline fan for exhaust (<200CFM for most 4" fans) is plenty to exhaust most small rooms or cabinets (unless you're really going overboard on lights). Since you are growing in such a small area, 2 computer fans blowing air OUT of the box and allowing room temp air to pass thru vent holes on other side should do the trick unless you are overdoing it on lights. CFLs don't really have a good light to heat ratio. You'd use less power and generate less heat by switching to a few small LEDs or adding those instead of more CFLs. DnkBuds.... 1000W for that amount of space sounds like a lot. 84F without CO2 is upper end of what makes my girls happy but spider mites sure do love it. I wouldn't recommend hanging wet towels in your grow room or lifting objects from WalMart. You're the one with the mutated seedling rightt? How's that going? Aloha spirits.
Omdogg....I want to get baked with you, dude. I've read several of your posts. You are spot on with your advice and give it with humor and tact. Cheers to you, bro.