Lighting and Ventilation question

mike91sr

mike91sr

Well-Known Member
So first off, this is my first post on the forum, I've learned tons and am hoping to learn tons more and contribute as I gain experience. I've grown outdoors for a couple seasons but this will be my first indoor grow.

I'm building 2 cabinets. The first will be for clones and early veg, the other will be for veg and flowering. I plan on doing a SCROG grow and going from there. The smaller box is 2'x3'x3'. I plan on putting a 125w CFL in it. This will just be to root my clones and get them a little bit into veg until the flowering box is available, just to save a week or 2 in each harvest. My cubic feet for the first box is roughly 18. I have a 42 cfm pc fan that I can mount up with a little creativity, would the be enough?The duct fans I have found are a minimum of 65 cfm. Is that going to be excessive? I also don't know if the carbon filter will restrict at all, reducing the cfm a certain amount. Regardless, either one *should* recirculate the air at least every minute, which is way more often than I've been told is necessary.

My second cabinet is going to be a stadium SCROG set up. The box will be 2'x6'x5'h. The total screen area will be roughly 20 sq ft (12 flat and 8 up the walls). The box will have a total cubic footage of 60, so I'm planning on using that same 4inch 65 cfm duct booster. I'm unsure about what wattage hps light to use though. Wattage per sq ft dictates I should have a 1000w, but I can't help but think that's really excessive for a box that size. I'm trying not to have too much of a heating problem, so I'm thinking 600w?

I will be posting up pics as the build comes along, and appreciate any advice anyone has for my setup! Really looking forward to this grow.
 
M

mrmadcow

Well-Known Member
a carbon filter will put a serious hurting on a pc fan. seedlings & small clones wont put off much smell so you may be able to do w/out.
as for lighting, a 6 foot wide box is a large area,a 600 will work but consider a light mover or 2 400s.(or making the box 3x4)
 
mike91sr

mike91sr

Well-Known Member
Thanks for the response. The way I see it, a 92mm 42cfm fan will still at minimum be able to recirculate the air every 5-10 minutes. And as they're going to be very small plants, that would be fine I'm assuming? Even if it only ends up flowing 2cfm, that recirculates it every 9 minutes. My only concern is whether or not it will actually pull through the filter and not burn itself out being overworked. I should also mention that I will be putting clones into this box and growing the plants to about 8-10", when they are ready to be put into the scrog box and trained. My outdoor plants always started to smell right around that size, and having a group of them in a small area won't be good.

Also, the other box will be 6 feet wide, but as it's a u-shape, I was assuming 2 lights would be too long. The raised edges will be too close to the outside of each light. My understanding was that the stadium or u shape was designed to make it so that growing area can be extended without being too far from the light in the center, allowing more space and yield for a narrower box. And I'd love to make a 3x4, but its going into a walk-in closet and the lady says it has to fit against one wall without blocking the "flow" of the room.... :wall: Lastly, wouldn't 2 400w lights put off more heat than a 1000w? As mentioned, I've never done an indoor grow and don't know how hard it will be to keep a box that size cool with a bigger light.
 
M

mrmadcow

Well-Known Member
mike91sr said:
....My only concern is whether or not it will actually pull through the filter and not burn itself out being overworked......
Click to expand...
my thoughts as well, you will only be able to tell by building it and testing
as for the lights, I didnt catch the stadium effect. a lights footprint isn't a square or even a circle but is oblong - less light at the ends so if you mount it horizontally w/ the base against the 6 foot wall, you will maximize usable light. ..good luck...mc
 
mike91sr

mike91sr

Well-Known Member
Well I built and tested it..pics too follow. You can feel a slight pull coming from around the filter...I'm honestly kind of impressed, I ended up using a 120mm 78cfm fan I found in an old box though. I think down the road I may change it, but it will work for now (running out of money on materials).

As far as the stadium goes, I understand the light reaches an oblong shape. The ends get less light, which is why they are raised and angled to bring it closer to the bulb. Mine will be similar to this one http://www.420magazine.com/forums/do-yourself/142952-built-nice-u-v-shaped-scrog-screen-16-a.html except that I will only have 1 light. Turning the light was also a part of the plan, I just have to decide if I can make the box that much deeper to fit the hood.
 
I

irieie

Well-Known Member
mike91sr said:
My second cabinet is going to be a stadium SCROG set up. The box will be 2'x6'x5'h. The total screen area will be roughly 20 sq ft (12 flat and 8 up the walls). The box will have a total cubic footage of 60, so I'm planning on using that same 4inch 65 cfm duct booster. I'm unsure about what wattage hps light to use though. Wattage per sq ft dictates I should have a 1000w, but I can't help but think that's really excessive for a box that size. I'm trying not to have too much of a heating problem, so I'm thinking 600w?
.
Click to expand...
there is absolutely no way you will be able to cool a 400w let alone a 600 or a 1000 with a 65 cfm duct booster.
 
iNFID3L

iNFID3L

Well-Known Member
ive got a 400 and i use a 467 m3/hr on an air cooled hood, can switch it up to 552 if i need to.
and a 190 intake.

my grow room, if yah can call it that is 1m x 1m x 2.8m
 
mike91sr

mike91sr

Well-Known Member
iNFID3L said:
i wouldn't even use a filter to start out with.
Click to expand...
I plan on growing the plants for 4-5 weeks after transplanting the clones into pots. I don't want to be forced to pick strains based solely on it having a faint smell.

irieie said:
there is absolutely no way you will be able to cool a 400w let alone a 600 or a 1000 with a 65 cfm duct booster.
Click to expand...
What would you recommend? My thoughts were (filter)-->Fan-->Light-->exhaust venting. I had thought of putting a 'T' on the end of the light and having 2 filters. Overkill? I also looked around at hoods and decided to go with 6 inch ducting for the larger box. There are 6" duct fans that push 250cfm, would that be enough to cool a 600? Or should I just get an inline fan from hydrofarm active that moves 400cfm?

I also plan on putting several fans in the box that will help disperse heat from directly reaching the plants.
 
jondamon

jondamon

Well-Known Member
DUCT BOOSTER fans are GARBAGE for exhausts, you need an inline fan.


I use a 600w in an aircooled hood with 400CFM/660m3h inline fan on a speed control.

I also use a 180CFM/280m3h inline fan for air exchange/scrubbing.

I can get my hood within 1inch of the tops of my plants by doing it this way.


For a 400w i would recommend at least 250CFM fan
For a 600w i would recommend at least 300CFM fan
For a 1000w i would recommend at least 400CFM fan

Above are the minimum CFM's to cool the light , this does not include extra allowances for duct lengths/bends/carbon filters.




J
 
Hoenhiem

Hoenhiem

Active Member
^^ i agree, with 400w you need more than 65cfm. and forget about a carbon filter on a booster fan. you would not move much air at all and you will still have heat issues. since im still waiting on my inline fan i leave the door open on my grow box roughly 4x2x2 and leave an osculating fan on it keeps my temps reasonable. im using a 400w hps but i also have a fan running for an outake about 42 cfm during this time.
 
mike91sr

mike91sr

Well-Known Member
Ok so assuming I get a large enough fan to cool it, will 1000w be overkill for a 2.5x6' box? I know most people on here recommend that you can't have too much light, but I don't want to have unnecessary light creating heat, causing me to spend more on ventilation, plus a higher electric bill. I've just read a lot of things saying 600w isn't good for anything over 4x4, maybe 5. Also, with such a long box, how should I situate my light? And will I benefit from adding 2 26w CFL's at each end?

Hoenhiem, do you keep the door open during veg or flower? I don't need my grow to be 100% stealth by any means, but I dont want people walking in the front door and smelling the plants immediately. People talk too much around here and although I'm doing nothing illegal, it's just not something I need everyone knowing.
 
Lilliac

Lilliac

Active Member
I have a 3x3x2 closet and im planning on getting an 80 cfm in line fan for exhaust, and one for new air from outside. would that be enough to ventilate it?
 
mike91sr

mike91sr

Well-Known Member
so i ended up getting a pretty killer deal from a buddy for a pair of 600s with hoods, electronic ballasts, and a few bulbs. This led me to want to build a bigger box to facilitate them...of course right? I'm going to build a 3'x7'x6'h box. Still planning on doing the scrog and making a small incline at each side; probably about 18 inches long, raising up 6-8 inches. With 2 lights, each one will have to cover a footprint of 3'x3.5', which is pretty solid for 600w's from everything I've read. Including the v shape, it will be roughly 22-23 sq ft. 1200w makes that about 55w per sq ft, again right on. Now I just have to upgrade the ventilation to keep up!! Looking forward to getting on with this build and getting some pics up. Thanks for everyone's advice
 
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