I have to try putting a positive pressure in the room. I have attempted to grow twice now and powder mold is kicking my ass. I think the only answer is to sterelize the room and move the fan from the exhaust to the intake. I intend to put a hepa filter in front of the fan and push filtered air into the room. It's not what I would like to do but I don't have much of a choice unless anyone has a better idea for keeping spores out of the room. At least if the room has positive pressure mold spores should not get sucked into the room from outside, and when I walk in it should push small dust particles away from the door. I can't let that shit beat me!! I'm not sure if that stuff actually infects the plant and it comes from inside the plant or if the only way it comes on is to attach to a leaf and root into the plant. Anyway, I don't want to turn this into a powder mold thread so if anyone has defeated this shit please PM me.
Powdery Mildew is a major pain, two things I can recommend personally are Serenade and GreenCure. They work with different methods. Sterilizing the room is best, if the PM keeps returning in non optimal conditions then it may be systemic (IE infected the plant). I have heard that Cloning and treating and cloning can remove it once it has gone systemic. Otherwise strip down sterilize with bleach and start from seed. IMO I don't think positive pressure will do it. I think the spores are coming from the infected plant and you / air bringing them in isn't the primary cause. HEPA filter on intake is a good idea though.
my grow closet is 2'x2'x6', which works out to about 24 cubic feet. i'll be using 2 90watt CFLs, and a 120mm heavy duty PC exhaust fan (~50CFM) to regulate temperature using an programmable thermostat does anything in that equation sound problematic?
I recently purchased this grow tent Hydroponics Tent 36x20x62 Home Hydro Cabinet Grow Box - eBay (item 220627395583 end time Jun-27-10 10:50:14 PDT) Once i set it up i realized i wont be able to use the back vent and probably the top vent, leaving me only the bottom left one. Is that a bad spot for a vortex 4" inline fan since its on the bottom sitting on the floor?
I would say screw the thermostat and take that money and buy additional ventilation a 120MM won't be enough to cool 180W of CFL imo. It might but it will run 24/7 if it does. I would say at the very least get a 4-6" $25 duct booster over a single 120mm PC Fan.
You would probably vent out the top. You can vent out bottom sure. But I would pull air from floor, and exhaust out top scrubbed. I would do it one of these ways... 1) If there is apace above that shelf I would absolutely cut a 4" hole. Put your vortex and filter up there accessible with tent closed and doors open. Run a short duct hanging inside making a 90 degree angle (otherwise let hang down 2-3") into the tent on ceiling. Other way would be to put scrubber inside tent on the 90 on the ceiling and maybe secure to shelf. This would scrub air at the exhaust collection site and probably do a slightly better job. But you use a little space inside tent and you would have to open tent to get to it for whatever reason. 2) Other way would be to mount fan hanging inside tent with scrubber attached there and then make a 90 off vortex UP below shelf (no cutting this way) and then let it dissipate in the space above tent and naturally tend to flow back out into the room but above intake.
Just out of curiosity, Would anyone happen to have a pic or 2 of one of the duct booster fans that comes without a cord wired to a cord or wired into a junction... I'm considering the cord route but I have access to a junction... Also any recomendations as to whetheror not I should go this route or wait until I've got $110 for a good fan as opposed to $35 for the fan and a DIY wiring job... Thanks!
I'm going to be starting a small grow in an enclosed space soon. I've been reading this FAQ and would like to make sure my numbers are correct. My space is going to be 45"x29"x66". This comes out to 86130 cubic inches, or 1.411 cubic meters. Assuming I want to replace the air every five minutes, since I won't be using CO2, that comes out to just .2822 cubic meters per minute. Considering heat for ventilation, my system will be running 18x27W light bulbs for a total wattage of 486W, or .486kW. Using this formula, V = Q / (P x C x dT), with my room temperature being 76F (24.4444) and my grow temperature area being 78F (25.5556), I get V of .3573 cubic meters per second, or 21.44 cubic meters a minute. So I would plan to go with the 21.44 cubic meters per minute, but that sounds a bit low. With a grow this size, would that be enough to cool it? If it is I could get away with some computer fans I have lying around.
The S&P Fan I bought I had to wire myself its pretty common. To wire it, which is the same for the duct booster fan, take a 110V computer power cable that comes with every device printers monitors computers etc. You or someone you know should have an extra. Next cut the tip that would go into the device (block end) and then you should have 3 wires, strip the tips of each. White Green Black or something to that effect (just google the 3 wires you have if don't match your fan) Green / Copper is always your ground. You might get blue or brown but probably white and black. Match up the wires and use wiring nuts or screws (S&P fan i did screwed in). EDIT::::::::::: I found this thread this morning that has pics of the wiring for a duct booster http://forum.grasscity.com/grow-room-design-setup/456055-step-step-how-exhaust-micro-cab.html
You need 21.44 cubic meters (i didn't check math since you showed your work) of AIRFLOW not rating. Duct bends / carbon filter / leaks etc will reduce your airflow. My advice is to go over what you need 18 27W cfl are going to put out some serious heat though (ballast part mainly). The google machine tells me that 1 Cubic meters = 35 cubic ft. So that would mean you are looking at a 735 CFM fan which doesn't seem low at all now. I am pre coffee converting cubic meters to cubic ft. But just from experience I would think you could cool 400-600W of CFLs with a nice 4" or 6" fan without problems, which would be less than 735 CFM. If you want to be safe go with a 6" just a bit harder to do DIY Carbon Filters but there are some 6" options for build or purchase available. 4" Centrifugal or Mixvent seems like enough fan to me but it wouldn't hurt to use a 6" that's for sure. Hope that helps.
Why 735 CFM? My dimensions are in inches, coming out to around 50 cubic feet. 735 just sounds very, very high. A single, powerful fan would be good but I'm having trouble figuring out how to contain it within the box I'm building and the space I have. I was thinking of running a total of 8 computer fans. 2 intake on the bottom right wall(1 front, 1 back), 2 intake around where the lights will be on the right wall(they will be adjustable in height so I'll put the fans as close to the middle as possible), and 4 exhaust fans on the left wall at the top. The fans I have should provide about 250 CFM of airflow. I plan on installing a homemade carbon filter system in between the exhaust fans and the outside of the box, but I don't think that would restict airflow too poorly.
I thought 735 CFM seemed really high too. You were mentioning cubic meters is all and so I thought you were converting to cubic meters 1 cubic meter = 35 cubic ft. I think a single 4" fan is the best way to go. Don't muck around with intakes and 10 PC fans, sounds like a huge headache to me. I would get a single 4" fan mentioned in original post and you should be golden. Take away the formula and a 4" fan i am referring to should do the job smashingly.
I would, but I'm having problems figuring out how I would install it. My box is going to have removable sides and a removable front panel(don't worry, I've got light-proofing down) and no real room in the back for an intake/exhaust outlet. If I were to mount a 4" fan on one of the removable panels, it would make it extremely difficult to secure easily and cumbersome once removed. The reason I'd like to try to stick to PC fans is the size and ease of mounting them. I could easily mount 4 to a panel without causing any issues. The intakes would simply be drilled through the panels, with a small attachment to light-proof it. If you know any ways to easily mount a fan on a removable panel, I'd love to hear them. I agree, it is a lot more work for the PC fans, just seems it would be the more feasable option in the long run.
Well you could mount it balanced in the center of a side panel and use a 4" adjustable 90 (made from sheet metal ~$4-8 at home depot). Then put carbon filter on outside with fan blowing out. I would mount this one THROUGH the side panel... now this would be lighter but you couldn't lay the panel flat after taking it off. if you drilled your own holes you could mount this on the side with the size of an 8" duct booster I would rather go with a 4" S&P its plastic construction makes it really light weight. ~5 lbs.
this looks like a good place to develop an idea to cool/exhaust my in-process micro grow box. it measues 20"x20"x36". I wont go into details about my box ...u can check out my thread in the link bellow. What I am doing is building a Peltier Module air conditioner. peltier module squirrle cage pc fan with attached monster heatsink to dissipate the heat smaller heatsink to help move the cold side of the module and a small pc fan to blow out the cold air When its all said and done the part will be enclosed and pretty much be a micro air conditioner wich will also serve to blow air out thru a carbon filter. all this is in the works ill take any ideas
Ok, I've been going over numbers more, and the formula for ventilation based on temeprature just doesn't seem to add up. All of the units are right, but I don't see how cooling required based on wattage would be accurate. Here is my take on it, based on what I know about the conservation of energy. The wattage of a light bulb is a measure of the total energy used. Most of the input energy is converted to light, while some is converted to heat(the amount we want to cool). Different bulbs do this at a different ratio; 150W of HPS or MH will almost always run hotter then 150W of CFL since the bulbs output light in different manners. If this is the case, the amount of airflow required to cool the CFLs would be significantly different than the amount required to cool other bulbs, such as the HPS/MH bulbs. The general equation would seem to only work in the case that all input energy is converted to heat, which is never the case. Any thoughts?
Great post man, +rep for that. I was about to go digging on forums looking for more detailed info on venting and odor control and what I need to set all my stuff up... And it was all right here! Thanks for all the info man, I will not even waste my money on an intake fan! I also am glad you pointed out that a 4 inch fan covers up to 600w (I am going 400, so I'll be fine) check the thread I started if you would like to assist me in making final decisions before I snag up all the new mats for my next grow. http://forum.grasscity.com/grow-room-design-setup/632115-new-setup-need-input-please.html