Noob's guide to growroom set-up : a work in progress

Shoulda coulda. We all don't like to change, and we definitely don't like to spend money. Both are a huge mistake. I don't think a grow should be without an environmental controller unless perhaps it is using LED or CFL lighting, and even then it would be highly beneficial. And I've had one of my ballasts on the floor under my a reservoir for 5 years now. It's easy, just be careful. Kinda like mountain climbing. One slip and your dead, so just make not slipping your main concern at all times. The ballast will move soon though, if I can pull my ass out of my ass for once.

OK-I'm going to walk thru cable routing kinda quick.

This is all pretty straightforward. We'll start with the cord that's going to run from your ballast to your lamp.

Remember, this wiring is on the HIGH VOLTAGE side of the ballast transformer. HID bulbs operate at a nominal 600 volts AC ( which, as trivia buffs may be aware, was proven by no less than Thomas Edison to be capable of causing a watermelon to explode, properly applied. Thomas Edison must have really loved his job.). There's a very signifigant start-up surge when the bulb fires- Peak voltage is determined by the bulb's cold resistance factor, but it will be notably higher.:wtf:

(Please Please Please don't try to add length to your lamp cord by splicing in romex or an extension cord. They're not designed for this kind of voltage, and very likely to fail. You can buy the right stuff @ Home Depot, if you have to splice in. Or better yet, just buy a longer lampcord and socket set @ your local hydro shop, if you're not very very comfortable with appliance level wiring. F#$king up is a good way to start a fire or fry a ballast, though it does make for interesting fireworks).

So, from the above, we can assume that we want this cable run very neatly, with nothing pulling on it, up off the floor- so we can't step on it, and it will not get wet. It's a very good practice to make sure that you can't touch the lamp cord and any exposed metal plumbing ( pipes, radiators, etc) at the same time.

So, let's start by lowering your reflector down as low as you can ever imagine running it. Now lower it another six inches. Toss a ceiling hook in up by the existing hook that holds the chain running to the socket end of your reflector, and loosely loop the lampcord over this new hook. I generally put on a cable tie, very loosely, so that I can still slide the cord easily, but I know that it's not going to pop off.

Have you thought yet about where your ballast is going to live? Ideally, a the ballast does throw some heat, we'd like to have it out of the room entirely- but this might be overly complicated. If you've sized your ventilation properly, it'll handle the ballast heat just fine.

I've only got one hard and fast rule about ballast placement- IT MUST BE HIGHER THAN MY WAIST.

Why? Because five gallon buckets full of water are heavy, that's why.

Simple fact of the matter is that you will, at some point, be carrying a full five of something in this room. On account of being a primate and all, the easiest way to carry a full, heavy five is by the handle, which puts it down by your knees and out away from your body. If you're short on room, though, or if you need to pour from said five, you're going to rest the base of that five on your hip bone- and that's when you're going to drop it.

Growrooms by their nature pose a high risk of accidental intersections of electricity and water. There's a reason why building codes require a UL listing for water heaters and washing machines- and these are the only things that I can think of in the average home that bring water and electricity into the same proximity as a growroom. ( OK, hot tubs and fridges w/ icemakers... I'll be over around eight, have margaritas ready...).

I was once standing next to a 1KW halide ballast that got suddenly, catastrophically wet. About 8 milliseconds later, I was sitting a good ways away- then running for a fire extinguisher.

Seriously, keep your ballast up out of the spill zone- water and high voltage transformer plates do not play well together!!

So figure out where you're going to put the ballast, and string the lamp cord over to where it's going. I just use ceiling hooks, myself. Run the cord as straight as possible across the ceiling and then down the wall to your ballast. Ballast sitting on a shelf is fine, but I like to actually hang them right on the wall. Quality ballasts will have some kind of rigging hardware built in- keyhole slots in the handle, or a bracket on the bottom of the ballast. ( You may have to pop the rubber feet out.) I usually don't bother trying to acoustically decouple the ballast from the wall, but if the buzz makes ya nuts, slip a couple of neoprene washers between the wall and the ballast when you hang it.

Anyway, ballast on a shelf is fine- if you can spare the shelf space. I'd be really surprised if you can't find anything better to do with that shelf, though. Ballast on the floor, though... not a risk that, to me, is worth the benefits. ( Hint- there are no real benefits. You're just struggling with inertia).

Same thing with extension cords and suchlike- up off the floor, and ideally mounted on the ceiling. I in fact have, more than once, had an extension ground out through a puddle and then through me. The sensation is really indescribable, and you really don't want to find out.

Plug the lamp cord into the ballast, and gather any excess at that end into manageable loops. Use a cable tie to secure these loops to your last ceiling hook. DO NOT plug the ballast into power quite yet.

Now raise the reflector up to the highest level that you will ever ever use it, and figure out what you're going to do with the excess cable at this end. I like a bicycle hook that I can throw loops over as they develop. Make it easy on yourself- make it easy to keep things neat.

Go ahead and put your bulb into the socket, remembering to wipe it down when you're done. The oils from your hands can cause hot spots on the surface of the bulb, which could cause ( rapid, spectacular) failure. I just use a clean paper towel.

Ok, take a break, blow a bowl, and get some sunglasses.

Ready? High? Feeling sassy?

Go ahead and plug that sucker in. You deserve it. ( Now you know why you wanted sunglasses.)

I don't know about anybody else, but the sound of a ballast getting powered just makes me feel like a little kid. Seriously, all warm and fuzzy inside...:D

OK, next thing to do is cable in the fan, but I think that we should go over environmental controllers before we do that. There may be decisions to be made about where to plug things in, and it's helpful to know why. There are also some things to know about how the controllers work, and what they need to work well.

Now that I know that people are actually looking at this, and I'm not just typing into the wind, installments will come much more quickly.

:rasta:This is really good information! I learned most of it when working with marine aquariums.

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reefkeeer: (ref-ke-per) n: individual obsessed with placing disturbing amounts of
electricity and seawater in close proximity for the purpose of maintaining
live coral reef organisms.
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Almost the same thing can be described for indoor pot farmers.

I did use a 15 amp extension cord to add a 4' lead to my ballast. More than 2 months and no issues, but I'm going to upgrade it ASAP. Any specific recommendations on what to use instead?

Another section that would be awesome would be completely light-proofing cabinets. I had (and to a degree, am still having) problems lightproofing my ClosetMaid (Home Depot) wardrobe.

Thanks for taking the time to write all this down for us newer growers! I don't think you really realize how many plants you've probably saved, and how much you're really helping to "overgrow".

Env. Controllers, at their very simplest, can be as simple as a thermostat that turns on an exhaust fan when temperature hits a particular setpoint. Most folks find that they outgrow that sort of rig pretty quickly.

Let's think about the temperature and humidity cycle of a room over a 24 hour lighting cycle. We'll assume that you're flowering at 12/12, and that the lights come on at midnight, which just makes the math easier. We'll use 24 hour military time.

At 0:00, your light(s) kick on and the room begins to warm. (If you just have a fan running on the same timer as your light, you may find that the coldest moment of the day is actually right after the light goes on, as the fan is sucking cold outside air into a room that's not hot yet).

By 1:00, the room is hopefully pretty warm, ideally at 70-75F @ an RH of 40-60%. Lovely.
If your fan is perfectly sized, it might even be kinda stable. More likely though, a slightly oversized fan is causing the room to run cool, or a slightly undersized fan is causing the temperature to slowly rise as the â?? dayâ?� goes on. The warmest point in the â??dayâ?� will probabley come near the end of the â??dayâ?�, around 12:00, when the light has been running for a long time and the outside temperature is going up.

Now we're in the dark part of the cycle, and temps are going down. Maybe.
Another scenario is that the fan has turned off, but the bulb and reflector are still hot. As the room's no longer being cooled, it's common to get a temperature spike before temps start going down.

As warmer air will hold more water vapor than cooler air per cubic foot, this temperature spike will cause a water uptake into the room's air- which is fine, until the room starts cooling down. As the room cools, the relative humidity goes up- and if it get's high enough, you can get dew.

The combination of high humidity and lower temperature will often cause mold problems.

So now it looks like we need to control both temperature and humidity, and we need to control them seperately from the lighting cycle.

The easiest, and pretty much cheapest, way to do this is with a purpose built environmental controller, like the CAP Air-1 or the Greenair CT-DH1. These units contain a thermostat and a humidistat that are each wired to apply power to an outlet when either temperature or humidity exceed preset conditions. They're designed to run an exhaust fan.

When you look at purchasing these, you'll be shocked at the cost- I was. Being a bit of a yahoo about making my own controllers ( I once rebuilt a Holley choke plate so that it could be controlled by a bicycle brake cable from inside the cab, as I was too cheap to replace the automatic choke element), I decided to build my own. A quick visit to the local electrical supply left me about $140 lighter in parts (humistat elements are wicked pricey), and then I spent a day figuring out how to paralell wire the two units. I should've just gone the $150-$175 for the pre-built, and I have ever since.

These units are the bare basics, and it's worth looking in the $200 range for feature sets that you think you'll be able to use. For instance, if you think that you're ever going to use C02, you'll want a unit that has an out let that gets switched off when the fan outlet gets switched on. You can plug your c02 timer or ppm controller into this outlet and be assured that you aren't releasing expensive gas when your fan is running. If you're using a cycle timer to control the gas, it'll reset to beginning of cycle when the fan goes off. Neat, huh?

I really love the Sentinal stuff- look at their EVC-1 at a street price of $200- very nice unit.

Anyway, let's go through the cycle again, but this time with a basic controller in place.

At 12:00, the light kicks on. The fan is off, so the room warms quickly to operating temperature. When it gets to the top end of operational range, the fan kicks on and cools the room to the low end of operational range. ( Thermostats use a built in hysterisis, or swing- the fan will come on a few degrees above setpoint, and go off a few degrees below- like your home heating thermostat in revere.)

The room continues this slight swing until the lights go off. If the room is warmer than setpoint, the room is cooled until it hits the low end of the range- then the fan goes off. The room will continue to cool until you hit the high end of your range for humidity- then the fan kicks on and flushes the damp air from the room. No dew- less chance of mold.

When you get into fancier controllers, they'll often have a â??night time onâ?� outlet- a built in photocell controls an out let that's only powered when the lights are off. Perfect place for a heater, if you need to use one.

If you have seperate temperature and humidity control outlets, you may choose to dehumidify with a dehumidifier rather than a fan, which doesn't cool the room. This makes it very easy to control low â??lights off tempsâ?�, or to keep inside humidity at appropriate levels when the outside humidity is very high. ( Think Alabama in August).

Your controller can also be used to run an AC instead of a fan- just watch out that your plants are getting enough fresh air or enough supplemental c02. Also, make sure that your AC isn't blowing unfiltered (stanky) air out into the street- most units can be set up so that they don't actually purge air, as it's more efficient not too.

An environmental controller is one of those investments where you get more from the third hundred that you spend than you do for the first two, and they scale up to larger spaces very well- think through your purchase, and buy all that you think you'll need for at least a couple of years. Going cheap and then buying better is often more expensive than just buying best to begin with.

When you mount the controller, make sure that it's exposed to good airflow- I like to actually have a fan blow over it. You want air from plant level, and blown over the canopy if possible. Mount it someplace where you can see it well and you won't jostle the knobs.

If you get a humistat wet, it's useless- either dead or so far out of calibration that it's effectively dead. Up out of the splash zone, as well as all associated power cords.

Hey, I'm sure people are reading and relishing what you've written so far. I still need to re-read all that you've said, but right off, I'd like to know how enclosed light-hoods affect your CFM ventilation calculations.

I made a spreadsheet with formulas so that I could goof with variables: room dimensions, feet of duct-work, number of 90 degree turns and such. Seems that your equations assume that the grow light is open to the room, rather than being hooded and ducted on its own, or in conjunction with the room's exhaust. I'd expect that if the heat did NOT leave the lamp and run all over the room, that it would be less of a problem to exhaust. It should be exhausted at its source (at the hood). This may lower the need for so many CFMs.

I'm planning two tiny veg and bloom closets (2.5 x 3 foot each, with 6-foot ceilings).

I'm going with a suggestion from stinkyattic I believe, to have my two grow rooms heat/cool each other by setting the light cycles out-of-synch between the veg and bloom rooms and exhausting one room into the other. Correct me if I'm wrong, but unless I get some solenoid-driven dampers to switch flow around as the lights cycle, it might be easier to just have an dedicated exhaust fan in each room, pushing one room's exhaust into the other. Of course I'd have some light-blocking feature so that the light would not bleed over between the veg and bloom rooms.

I'm thinking of just having both veg and bloom rooms exhaust directly through their cooled lamp hoods continuously, with their own dedicated can fan directed into a separate carbon filter. The outflow will be directed into the other room, and I'd adjust it if I see the temp in either room rise above 78F. The extra cost of duplicate fan and carbon filter will allow for some redundancy (e.g., in case one fan gives out), and the two carbon filters will last longer since there are two of them. But, two fans will use more electric power and add some heat on their own.

The other possibility is for me to include ductwork INTO both enclosed hoods and exhaust them without any carbon (odor) filtering. This would draw clean air into the light hood, past the lamp, out of the hood and out of the grow room. I'd ONLY filter the air from the ROOM itself (the air that is in contact with the plants). This is more complicated than I wanted to get, but is an option if I get some consensus here or impetus to pursue it.

What do you think? How much would directly handling the heat from the lamp/hood change the required CFM to properly ventilate a grow room (or specifically, a veg and bloom room exhausting into the other room)?

I'm more concerned about the NOISE of the fans rather than the added cost of two fans to exhaust the two rooms. If I think long enough, maybe I could figure out how to do it with one big can fan instead of two smaller ones. But again, stealth dictates for me to go with less noise.

My guesstimations absolutely assume that the hood is not cooled- There are just too many variables regarding reflector design to make any kind of meaningful guesstimates.

Could you post up the spreadsheet somewhere? It might save folks some work. Great idea.

I'd probabley just circulate between the two rooms with a couple of 6" muffin fans. You can pick up " starter flanges" intended to run 6" round off of box style manifolds for forced air heating systems- If you mounted one @ the top of each room, w/ the fan blowing thru the partition, thru the flange, and into some 6" flexi that leads down to floorish level in the other space, you'd get a nice flow pattern and built-in light proofing. Should be pretty cheap if you go Rat Shack for the fans. I def wouldn't screw w/ duct solenoids @ that level- too pricey, too complex. Neat, though...

If airflow between partitions is good enough, you can just put the filter wherever's conveniant. You could also use one fan on the exhaust, w/ a y-splitter on the intake and maybe an odorsok in each space.

Don't forget that on-time in veg will be longer than in flower, so there will be an overlap period when both lights are on.

I would def recommend using a ventilating the lights seperately- suck in clean air from outside, blow it over the bulbs, and outside again no filter. Just make sure that all of your joints are airtight, so that you aren't picking up stink from inside. Use the aluminum tape- duct tape will go soft at temperature. Seems more complicated, but it's actually simpler, as this fan is set&forget, and it takes a lot of load off of your main vents. Doesn't have to be much of a fan for a couple of 400s. If'n your feeling sassy, you can stick this fan on a thermostat, which turns it off if temp goes low- allows you to set a temperature floor.

The fans for inter-room exchange and yer hoods should be pretty quiet- the only noise issue is the primary exhaust. You can cut noise by using a larger fan on a speed control- fer instance, you need a 4", but you go up to 6" and cut the fan speed in half- greatly reduces noise. You'll also find that you can tune the sound of the ductwork by varying it's length- imagine a pipe organ.

Sorry I can't be more specific about hood flow interaction, but there are just too many variables, including changes in ductwork length/shape as the hood moves up and down, to make big sweeping statements. If you can be more specific about the hoods involved, I can tell ya what I see...

Hope this helps.

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Originally Posted by MaryLane

Great thread! I'm learning a lot. Now you need to do one on cabinet growing. :)

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^^^^^

Thanks for confirming that some of the things I've been planning (and didn't mention) are in agreement with your suggestions, and for the following ideas:

1. I'll look into the washable carbon filter, Odor-Sok.

2. For the exhaust/odor-control, I'll use a speed-control to cut the RPMs of a larger fan, thus reducing the noise (as compared to a smaller fan blowing full-tilt!).

3. It hadn't occurred to me that a muffin fan running continuously can move a lot of air between the two closets. And when you consider that a small muffin fan cools a PC which uses 200-250W, a muffin fan would probably cool the enclosed lamp well enough.

What CFM would cool a 400W enclosed HID lamp if the ducting were simply straight through (with just 4 feet or so of ducting)? I can use your exhaust formula to take into account the true loading: 3 to 4 feet of flexible ducting, either:
a.) entering and exiting the TOP of the closets (to avoid two 90-deg turns had I cut holes in the closet SIDES) snaking down, entering/exiting the lamp, then up/out, totally to 6 to 8 feet while making only two 90 degree turns, or
b.) entering and exiting the closet sides, with two additional 90-deg turns, as compared to situation a.) above.

I'm not committed to a particular type of hood yet (I'm still planning my first grow!). I'm thinking about a home-made glass bake tube, or perhaps will spring for a store-bought enclosed hood with a large reflecting surface.

Oh, and I'm working on finding a safe place to upload the spreadsheet with all the exhaust-loading formulas entered. Any suggestions to protect my anonymity and security, while still sharing the file?

Look at SuperSuns from Sunlight Systems- they're discontinued now, but they had a really unique air cooling arrangement that might work well w/ your layout. Nice little footprint, too. I'm sure somebody out there has a couple in the back, still- or you could call Sunlight and see if they can help ya find some.

The SuperSun, not the SuperSun II.

Are we talking one muffin per reflector or one muffin running both, with ductwork interconnect? If we're talking one per reflector, I would just grab whatever is cheap and easy in 6" muffin- it'll do ya, go w/ any reflector that's got glass and 6" flanges.


If you wanna run two fixtures on one fan- muffins won't cut it.
You've got a fair amount of duct drag, so fan design gets to be an issue- if yer going 4", you'll probabley need more than a muffin, regardless of free-air cfm. Even @ 6", tho better.

Guesstimate that 70cfm throughput is gonna be overkill, depending on exterior temperature. Overkill here isn't a bad thing- you can always dial down.

I'm sure a 4" in-line would be more than enough, even dialed way down.

Have a look at bathroom exhaust blowers down @ the depot- they might have something cheaper than a grow-store inline, since you don't really need all that high a SP rating- but more than a muffin.

Ya might wanna flow it so that heated air moves from flower to veg- if it runs a little warmer in veg, it's not the end of the world.

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Look at SuperSuns from Sunlight Systems- ...

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I'll look at the SuperSuns (as I can find 'em), not the SuperSun II.. tho I'm having a problem Googling 'em. And I'll look at some bathroom exhaust blowers.

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Guesstimate that 70cfm throughput is gonna be overkill, depending on exterior temperature.

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This will be a basement grow where temps are maybe 65-70F that time of year. So, I figure there is a giant heat-sink in the basement to dump any excess heat. I think I appreciate when folks say, "Basements rock!". With minimal basement exhausting, and perhaps some kind of CO2 enrichment (or more accurately, some CO2 remediation) I'll be fine. I wish I could measure/monitor the CO2 cheaply.

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Ya might wanna flow it so that heated air moves from flower to veg- if it runs a little warmer in veg, it's not the end of the world.

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I can appreciate that the temperature in the bloom closet is much more important/critical than that in the veg room.

I'll try to post about my plans, otherwise I'll post some kind of log here. I've really learned a lot here so I feel that most of my plans will get a few nods (if not a few nod-offs!).