Beginner's guide to grow cabinet design

Ive made this thread to share some of the information ive gained in the process of building these things.

it is targeted towards people who havent attempted an indoor grow until now. I am working on my second personal design and ive helped with a couple others. nothing significant, but hopefully it helps some new builders along the way.

Ok! So youve decided to take the plunge and build a grow cabinet!




Great. now what?

well, a disclaimer.

I am not responsible for anything illegal or stupid that you do as a result of reading this document.

Im assuming you are growing for medical use and posess a card.

who is going to jail if you get caught-who lives with you? first and foremost, are they Ok with it?

more importantly, are YOU comfortable with the fact that your roomates know about the grow?

considering if they know, then their bf/ gf/ wife/ brother/ sister/friend etc may end up knowing as well...

if you rent, do you think that your landlord would stop by often, without notice? would he check on your house while you're gone if he got suspicious?

do the people who visit your house bring unwanted attention? if Johhny crackdealer stops by with bricks of weed in a bag once a week, do you think you should have a plant in your closet?

and, the classic, can you keep your lips closed?

if you are unsure about any of the above, I would reccomend taking a day or two to think about your choice. especially if you like to "share" information that shouldnt be shared when you smoke with friends.




Ok. onto the fun stuff.


first, lets decide on a general mental plan for your cabinet. all we want is general idea of what we are dealing with as far as size and usage.

as we progress onto lighting, ventilation, and other ideas, your cabinet design (including size) will solidify mentally.

1.0 do you want to build a single chamber cabinet, or a two chamber?

Single chambers are good for say 1 grow a year and an abundant source of seeds- or a good, safe supply of clones. longer wait times between harvest season.

double chambers are good for instances where seeds, or clones, are short in supply. you can keep a mother for free clones and run a perpetual harvest. shorter wait times for harvest season.

2.0 How do you want to grow your plants?

SOG, SCROG, LST are all ways to stunt a plants growth to limit its height. search for any of them and you will find a wealth of information on this site. you could probably grow a plant to maturity using these techniques in a cab shorter than 5 feet.

Naturally Grown plants require a grow cabinet height of 5 feet or more to comfortably fit the plant and the equipment. there are shorter designs that can be made, yes, but it can be a project to do so.

Hydroponically Grown systems require some thought ahead of time so that you can plan your resevoir size into the design.
maybe you want to try to match the footprint of the cabinet to fit a rubbermaid container comfortably?

Soil Grown systems can be fit into just about anything you choose for a growing box. there are a mass of differently sized and shaped containers for sale on the internet.

3.0 Can you build this thing yourself?

Pre-built cabinets are great for people who dont have the time, skills, or equipment to do so. Start researching Mills Pride cabinets on the internet as they are popular, and well priced. this site has some nice mills pride cabinets around, so search for them.
Home-Built cabinets are great for people who do not fall into the previous category, and want to custom build it how they want it. it can cost more time and money than buying a cabinet.



Now that you (hopefully) have an idea in your head about what your goals and what size of growing cabinet would best suit you, lets start talking about whats on the inside.

Ventilation


Okay. where to start?

Well, a good rule of thumb is exchanging the air 5 times a minute when you are trying to cool off a cabinet with HID lights such as HPS or MH. fluorescent lighting makes your ventilation requirements lower, since they dont throw off as much heat.

with a smaller fluorescent design, you could probably get away with only replacing the air once a minute, although id still reccomend shooting for two to three times since your ductwork and any type of odor control will usually cut your CFM's in half to two-thirds.

if you are working with a smaller design for a grow, such as a box or cabinet destined to go into your closet, here are some numbers for you.

100 CFM will cool, and ventilate a 150w grow nicely.
180-220 cfm will usually cool a 250w grow nicely.
250-400 may be needed for a 400w grow, as im assuming you have a larger box as we go here.

It would not be reccomended to install a 1000w light into a smaller growbox that is headed to the closet. even 400 is pushing it.

a 90 degree elbow in your cooling design adds enough backpressure to be equivelent to running an additional 15 feet of ducting. watch those elbows.

also, smooth walled ductwork is much better than anything with ribs in it, such as a dryer vent or a bath fan vent tube. if you have ductwork that has ridges on the inside, such as a dryer vent, stretch it tight to get the smoothest possible surface on the inside of the ductwork. ridges on the inside will create roughly 1.5 times the backpressure installed in this way. crinkled up, with a lot of "valleys" and "mountains" on the inside, you will have up to 2-3 times the backpressure of a smooth walled duct system. turbulence will kill your fan.

a cheap, light, and thin PVC to look for is sewer pipe, like the kind that would be used in a drainage field. it is much thinner than the other types that are used to protect wiring or run water lines. you can find 4" and 6" sticks of this pipe at home depot, although you might have to work a deal to get anything less than a 10 or 20 foot stick. it is an ideal material, because it is glass-smooth on the inside, and it can be heated with a torch to create custom bends to work with your cabinet.

enclosed blower wheel-style ventilation fans are the best way to go. for instance, a bathroom ventilation fan, or a stanley blower from home depot. these use a blower wheel fan design that are designed to work well with backpressure. if you have a smaller design, go with a panasonic whisperquiet fan, as they are the quietest on the market. these fans will cover up to about 200-250 cfm quietly. I use a 120. anything beyond 250 cfm should be left up to a Lasko or a stanley blower. you can find many examples of both bath fans and stanley or lasko blowers being using with the search button on this site.

a non-blower type fan, like the kind that you would buy at walmart to circulate air in the room, or in a computer case, are best suited to just that: circulating air within your grow room. its not a bad idea to get a bit of a breeze in your grow room, as this will eliminate hot spots and humidity pockets within your room, and the gentle swaying will strengthen the stems of your new plants. as far as using them for a growing box, I wouldnt do it unless you are building something small like a PC stealth case. these types of fans dislike any backpressure or resistance that comes from ducting and filters, and will become more and more inefficient as the backpressure increases.

when using a stanley or a lasko blower, a lot of people have built a chamber especially for the blower. this way, the blower creates a vaccum in the afforementioned chamber, and if you have multiple chambers to cool, all you have to do is run some ducting from the chamber to be cooled to the vacuum chamber. this makes your ductwork much easier in a two chamber design.

your HID lighting system will get very hot, even as a 150w unit. it is nice to run your air that is headed out of the cabinet over your light to keep it nice and cool. a good, simple solution for this is to use a home-made cooltube. these are made with a 4" round pyrex cylinder known as a bake-a-round. you can purchase these off of ebay, and you can find many examples of them being used on this site with the search button. in a nutshell, you build your light inside of the pyrex cylinder, and duct a ventilation fan to one end. the air in the box is sucked through the tube and around the light and then vented outside of the box. a downside to this design is the fact that the lightbulb will take up a considerable portion of this cooltube, which will make the ventilation fan much more inefficient. consider using a coleman lantern globe, or some other type of large, glass cylinder that would allow for more airflow.

You will have to vent the air inside of the cabinet, outside of the room. if you just vent into the room that you have the cabinet in, humidity and heat will build up. you have to find some way to get rid of that vented air. you could vent into a chimmney though a cleaning hatch. you could vent underneath your house into the crawlspace. you could vent into your sewage line through your cleanout inside of the home, which is a nice solution since you dont have to worry about odor control. you can vent outside through a window stealthily if you get creative with a fake window planter box that has a vent on the bottom. perhaps you could even incorporate a carbon filter into that planter box that has a lot of surface area, making it very efficient at removing odors yet also very easy to force air through..... hmm.....

if you have to cut through the floor to vent under your home, remember to go underneath to check for obstructions in the location that you plan to drill. I used to be an electrician. please, please check under your home to see what you are going to drill into. sometimes a nice solution is to take a long, thin nail and paint the tip orange with paint. then pound it through your carpet and floor so that you can find the tip on the underside of the house and see what you might have to work around as far as wiring, water lines, studs, etc. if you do have to move around a bit, you can measure off of the nail. and when you pull the nail out, you wont even be able to tell it was there.

Free grow box tutorial

You may also find this free grow box tutorial helpful. You can download it from the cabinetsonwheels website.

Haha, resurrected this one from the dead.

umm...

what if your box/cabinet is small enough not to need duct work and simply opening the door a couple times a day is good enough to fully exchange due to not being perfectly air tight (or for that matter doesn't even have light traps)?

Good morning,

Thats good for those couple of times when you manually open the door to exchange the air but, what about the times that are needed when your not opening it manually?

Do you think that the couple or even few times you manually open the door is enough? I don't, but it depends on alot of factors..
How much light your running and what type?
Is the room its in a living space such as in a bedroom closet or in the basement where room temps might be lower?

Plants produce fresh oxygen that needs to be exchanged with freshly "polluted" air for them to function properly. This exchange should be automated and allowed to happen more often then just when your awake to open the door the couple of times in a day. What happens to them when your not at home for whatever reason to open the door?

If its like my grow op, that lacks any type of ventilation system at this time, they suffer because i'm not there to unroll the window covers and open the window, let alone the unzipping of the tents for them to breath properly, never mind the fresh air intake.

Have a Great day
don

so, put a couple small holes and a small fan in it for passive air flow?