So I have been asked and often see questions about where to start when designing a grow room.
I have just built one and thought this may be a good opportunity to explain how, why, where etc.
To begin with, any space needs access, being able to get into the space is important, even if a cupboard grow, you still need to get in there.
There isnt much point having a space that has no electricity supply near it. If using HID lights, you will need lots of plugs for fans etc and if hydro, you will need more!
In my case here, I need around 8 sockets. HPS ballast, Extractor fan, intake fan, air pump, water pump, oscillating fan, uV-B light and I will be adding a humidifier and probably a negative Ioniser.
I try to keep as many connections outside the grow space as I can, mainly since there is heat genetrated by items such as the ballast and it may get wet in there with using a hydro system. Always keep plugs and extentions off the floor.
If you can get a space with a water supply, this will save having to carry buckets of water around. As you will see, the capacity of res's I use is around 30l, not a small amount of water on res change days.
So your space has electricity and power, you also need to be able to bring in fresh air and exhaust stale air. I cannot stress how important this is.
Beginners often make the mistake of underestimating how much air is needed for big fat girls.
So I have a space I wish to use, it meets all the requirements listed (except water supply) so I am good to start designing what I need to get this space up & growing.
The first thing I do is line the space with white polythene. This helps keep the space clean, gives some reflective light and encloses the space. So it is more or less sealed so, it will give me negative pressure, keeping those smells down.
You have negative pressure when there is more air being exhausted than supplied to a space, this means fragrant particles can only escape via the exhaust fan, which should ALWAYS go through a carbon filter.
I always begin by measuring the dimensions of the space, this will give me an indication how much lighting and extraction will be needed.
After lining the space and measuring, I have a space of 36" deep by 26" wide with a working height of 8ft.
After allowing for an oscillating fan, I have an effective canopy area of 26" x 26" (650mm x 650mm) 4.7sq ft (0.42m2). Quite a small area but one which, once dialled in, should be yielding me a minimum of 1g/w dry. This is often seen as the holy grail for many growers.
I see it as a reasonable benchmark to aim for. I think it was Gorges Cervante's who said anything less than 0.5g per month per w was wasting your time. I understood this to mean 0.5g/w flowering under HID lights. Quite often, the weight attributed to a strain will be quited per sq m. SO when you see a strain which can yield 600g/M2, this is under a 600W light. Funny how this equals 1g/w.
The best yieldsd I have achieved were around 1.7g/w in a very well dialled in room with a strain I had been growing clone to clone for over 3 years. It was the easiest growing imaginable and is the basis of what I try to achieve in a grow space in terms of lighting, ventilation etc. The rest is down to genetics and me! (That last bit is scary)
This dimensions of the space tells me how much lighting I need for the space.
To grow effectively, with nice dense buds, mary jane needs a MINIMUM of 3,000 lumens of blue (6,500kelvin) spectrum light during the vegitative stage and 5,000 lumens of red (2,500 kelvin) spectrum light while in the flowering stage.
As long as the space can be cooled, more light is always better. I like to aim for at least 7,000 lumens in flower and 5,000 lumens in veg.
So, in my space of 4.7 sq ft, I need a minimum of 23,500 lumens during flower.
These are examples of how much light some popular HPS bulbs emit.
250W HPS c 30,000 lumens
400W HPS c 55,000 lumens
600W HPS c 95,000 lumens
1000W HPS c 140,000 lumens
As can be seen, I would have enough light with a 250W HPS. However, I get a much better deal on a 400W HPS.
I buy a Maxbright 400W dimmable digital ballast including bulb and a shitty reflector for £90.
Filter & light.jpg
Extraction, movement & intake .
All plants need CO2 so grow. It is used in photosynthesis along with water and light and get converted into energy (starch/sugars).
So fresh air is needed around the leaves (the site of photosynthesis)
How you get your fresh air is one of the skills of designing a grow space. I get my fresh air from the crawl space between the upstairs floorboards and downstairs ceiling. This air is very good to use since it actually comes from outside via air bricks in the building so is fresh. Also, it is cool in summer and warmer in winter so a good source.
Windows can be used for extraction but are troublesome since neighbours can become suspicious of open windows in the middle of winter.
For the plants needs, it is better to exchange the air a minimum of 4x per hour, so once every 15 mins. This will provide enough fresh CO2 for the plants needs, however, if using HID lights, you will need a hell of a lot more.
I find if the air is exchanged more than 4x per minute (every 15 seconds), your humidity will drop dramatically, even as low as <10%, which is not good for your plants.
So I tend to try for around 3x per minute. This gives a nice balance of reasonable humidity, and managable temps, depending on the ambient temps.
There are 2 things that can effect the suction power of an extraction fan, carbon filters and bends in ducting. I will be using a carbon filter (Rhino) and the ducting will need 2x bends. For the carbon filter, I allow for a 15% reduction in air movement and for each bend in the ducting, I allow another 10% for each bend.
I am using the modded fan regulator so I can vary the high & low speeds of the fans and at what temps the exhaust fan turns on.
As was seen above, the space has an area of 36" x 26"(650mm x 900mm) with a height of 8ft (2m) giving a volume of 56sq ft (1.17m3)
So the fan needs to be volume x 60 (this gives m3/h figure) 1.17 x 60 = 70.2M3/h for 1 air exchange per minute, I want a min of 3 and a max of 4 which means my fan, without reductions needs to be rated at between 210 and 280M3/h but this is the net figure, remember the bends & cf?
For the filter & bends, so 100%-15%(for filter) and -20%(for bends) means the fan rating needs to be around 1/3 higher than the air exchange I need.
So, 210 or 280 +50% means my fan needs to be between 315 and 420m3/h
I bought a 5", 355M3/h Ruck fan for the exhaust.
For intake, I want a fan slightly less powerful than the net figures.
I use less powerful than the net figure so I have negative pressure. Negative pressure means that any air leaving the space must go through the carbon filter, which means it is scrubbed of smells.
So I am using a Vents 5" 200M3/h.
Finally, no more maths!
But there is one last thing needed for any grow space and thats an oscilalting fan. I often use 2, one above the caopy, moving the air from the space between the tops of the canopy and the bulb. This will help get your light an inch or 2 closer. If I am SCROGging, I also have one blowing under the canopy since this is an area that can attract mould.
I recommend a small oscillating fan here once into flower, I just dont think on, even in such a small space as this is enough.
Thats the main elements for any grow space.
My aim is for Air temps at canopy level to be 25c (78f) and I want this no matter what the ambient temps outside.
Humidity is also very important. In veg, between 30 & 65% is acceptible. I like around 50% but extracting as much air as I am, humidity, even with a humidifier is going to be an issue until the plant is transpiring quite a bit. SO I will have to make do with humidity of around 30% until maybe week 4 of veg when it should increase to over 40%.
When flowering, it is imperative to keep your humidity beliow 50% to prevent budrot.
Whenever I see pics of budrot, I feel terrible for whoever is the unfortunate grower, vegging for 6 weeks, flowering for 8, then finding budrot after 14 weeks of work is soul destroying and all for the sake of keeping humidity lower.
In the space I have here, I could maybe squeeze 2 or even 4 small plants in, but I will only be growing one at a time and SCROGging to try to get the yield up.
I will be using a modded DWC setup.
The bucket in the grow space is a standard 20l DWC bucket familiar to anyone who has been in a grow shop. They are cheap as chips at around £6 and do the job nicely.
In order to increase the res size, I will be connecting this to a bin. Yes, a 40l kitchen waste bin, £6 from ASDA.
I am using a bin since at first glance, it looks like a bin! This is important since it will be sitting outside the grow space.
2 reasons for this.
1, it is much cooler outside the grow space, meaining by circulating the water between the bucket & the bin, it will cool the water temps.
2, I dont have to go into the grow space to check ph or EC. I still go to check the plant daily and to record temps but other than that, I want my plants to have a peaceful life, without some ham fisted grower poking around in there.
I am out of cash now, so I am improvising with what I have lying around. I connect the 2 with 3x sections of hose pipe and some connectors.
I am using push fit connectors, with taps, so I can remove sections while the res is still full. This is important for maintenence and you just never know when you will have to move things. I like flexibility.
The circulating will be done by top feeding the plant bucket, from the external bin, with gravity being the power behind the return.
The dripper ring is a home made job with a 1/2" "T" pi3ece and a section of hose pipe and a load of drip nipples. I think it cost me abour £1. What I like is the spray from these nozzlels gives even more DO.
I am top feeding for 2 reasons,
1, It creates a waterfall effect, giving me some DO
2, There are roots above the water line, which can and do absorb water, & nutrition. I believe this is why Sharks mod was so successful, he used all the benefits of DWC and Waterfarms. This is what I am trying to do here.
Bucket & pump.jpg
I am using 3 pieces of hose for the return for a few reasons.
1, it gives me the return the pump demands. I am using a 620l/h, Maxijet 700.
2, If one of the pipes get filled with plant debris or a piece of clay pellet, it can still drain.
I have not fitted an overflow pipe since this is a temporary arrangement and I have had wet feet before.
The bin and bucket give me an effective water capacity of around 30l, but with a couple of adjustments I will be using 20l. I do this by raising the grow bucket. I like a raised grow bucket so that I can direct my intake air supply at the bottom of the bucket, giving me added cooling.
You do not want your water remps to go over 21c in hydro. This is the point where pythium can start to take hold since water looses its ability to retain Dissolved Oxygen.
Pythium is omni-present (its always there) but with high levels of DO, it does not breed too well, once over 21c, DO levels drop down to something like 16ppm from up to 25ppm between 16 & 25.
You may get away with higher temps if you are getting higher levels of DO via flooming, waterfall effect or air stones.
For water temps, try to get them between 16 & 21c. Below this, the plants groth will slow, if not stop all together.
Bucket & pump.jpg
For bubbling the bucket, I am using an Hailea V-20 Water Proof Air Pump With 4 Way Manifold. One of the outlets will go to the bin since this is where adding nutrients will be done. The other 3 outlets will go to individual air stones. I have had bloackages in pupes and see it as common sense to have more than one air stone, just in case. I dont want a dead plant for the same of a blocked air pipe.
For air stones, I just use the cheap 4" stones from Pets @ home. I see these as disposable since all stones disintergrate over time. I like the look of the 8" volume air airstones, they are huge but cost £15
I just use the 4" netpots. I like this size since they are big enough to house a 4ft plant comfortably and they are small enough so the roots dont take long to come through.
Clay pellets. I soak in a 1/4 strength nutrient solution with 0.5ml per l of hydrogen peroxide (a natural cleaner), ph'd to 5.5 for at least 24 hours, then rinsed with water with the chlorine removed. I use this type of water because I will be using beneficials and I dont want any lurking chlorine to kill them all off!
Whate else do I have in the space. Thermometers & hygrometers.
I have a thermometer above the light, at canopy level and a probe checking water temps.
I also check the humidity at canopy level.
I have a sticky trap in case some bug finds its way into my space, though I have a filter over the intake fan.
What else do you need to grow with?
ph+ or liquid silicon.
A good grow book
Membership of this forum
Half a brain.
Last edited by Grub; 15-05-12 at 09:30 AM.
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Nice thread Woodyj
It will be alot of help to alot of people, As most of your threads are
Sweet set up bro,nice thread
Nice setup mate. Very well written thread aswell.
Nice thread Woody thanks for you time and trouble.
Excellent thread woody, Great info, something there for every one, and with my half brain I understood it, Cheers.
Brilliant thread Woody mate, full of all the info needed and put into simple enough wording for us all to understand. Cheers for taking the time putting it all together mate - I'm sure it will help lots of people.
I think it should be a sticky too Mods as it would of helped me alot when I was a new grower as it covers all the subjects needed to start to build ur groom.
Cheers again dude.
Friday Scrog's AK47 - Autopot Styliee
Friday Does Critical & AK47 Shrubs - Autopot Stylieeee
great read good luck with the grow..
Great thread, very helpful. You should write a book woodyj. I automatically read a thread if I see you've posted in it.
You are all too kind with your comments.
Makes me quite humble to know I've helped a few guys out.
I have been meaning to write this up for a while but time has been the issue. I just hope someone gets some benefit.
Thanks again guys.
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Nice and detailed mate, can you tell me where you got your " Maxbright 400W dimmable digital ballast including bulb and a shitty reflector for £90", i can't find them for that price for love nor money
The guy has a new online shop now and it seems either I got the4 price wrong or it has gone up.
He is about the cheapest around, next day on most items and excellent customer service if there is a problem.
Last edited by Grub; 15-05-12 at 09:32 AM.
Reason: Link to grow shop removed. (Greens only mate).
if i'm injecting co2 at 1600ppm,the plants are in oxypots,the big koi pond pump is outside the tent sucking in fresh air to the airstones,(root zone), do i actually need to suck in fresh air to the tent,the 4 x 400w hid's are air cooled and preety much 90% sealed with glazing silicone,allowing for a little extraction(plant by-product produced oxygen)so my question is if the plants are getting all the co2 they need and the roots are getting all the oxygen they need do the plants(leaves) still need standard oxygen or is co2 all that they absorb.
i'm using an airconditioner and nutrient chiller if this helps.
1st. Paradise - Opium
2nd. Paradise - Jacky White
3rd. Paradise - Bella Donna
4th. Paradise - Spoetnik#1
5th. Paradise - Lucid Bolt
Good stuff m8...
Well done Woody. Thankyou so much. I think ill build a room very similar to yours. I have the added bonus of already having a chiller though
top marks and Thankyou for taking the time to write it..
Thanks Woody. Will help me a lot as a newbe , thanks
Good thread Woody! I certainly put an oscillating fan under the canopy as well 'cause i don't want to see bud rot since i'm lst'ing. Thanks!
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