First time large grow box (2x1x2m)

Hi guys.

Just wanted to get some ideas/comments/advice on my plans. This is the planned set up.

Internal box dimensions, W1000mm x D1000mm x H2050mm in each box, 2 boxes side by side made from 2x2 planed timber and 9mm MDF (changed from 18mm ply to give better quality surface and its cheaper). Plan to use one room for vegging and one room for flowering/hanging/drying. Planning on using a single 250W lamp in each, one with Metal Halide and one with Sodium. Wanted to grow 4 plants at a time (giving a 500mm x 500mm space per plant), once they are ready for flowering, change boxes and take clones to start another 4 new plants in the veg box, then cycle it like that.

Plan to have intake holes at the base and a single exhaust for both boxes at the top using a splitter. This will go through a carbon filter to take out the smell. Looking to install a pair of 120mm PC case fans inside each box for air flow. White paint for all the inside of the box, later upgrading to a high quality reflective material.
I think it would be easier to maintain temp if i keep the light static and adjust the height of the plants using shelves rather than adjustable lights, that way i can change fans/cooling to suit the lights output to heat the box enough to keep it around 25 degrees c.

I wanted to run the boxes empty for a couple of days to see how hot it gets etc and filling 4 pots (no plants) and watering the soil in the pots to see what varying humidity levels i can expect at any particular time. It will all be trial and error but i would love to get as much checked and stuff before i actually place any plants in there.
Will purchase 2 digital temp/humidity gauges, one for each box. The plants will be soil grown with the highest grade soil i can find (any suggestions?) and i plan to use various nutes in stages. I dont know if i should go as far as using moisture gauges to judge watering, i wanted to use the soak then wait till completely dry method, but is this flawed?

I have ordered 5 Super Iced Grapefruit seeds from Rhino, expecting one single plant to survive, any more will be a bonus. I hear these seeds are easy for beginners, as i have never done anything like this before, and i would just like some feedback on my plans from experienced growers and point me in the right direction in case i am making any drastic mistakes.

I am looking for the highest quality and yield possible from my set up, so please feel free to suggest particular lights, wattage, brand of bulbs, soils, paint to use inside the boxes (will have to be something water resistant, and silicone seal the edges of the box?), anything i have missed out or made a mistake on, as all the information i have gathered is from various sources on the net.

The boxes will be placed in a detached modern garage. It is reasonably well ventilated, and i dont plan on the operation being any bigger than 4 flowering plants at any one time.



So please feel free to pick my plans to bits, as this is all just the planning stage at the moment. Money is not exactly a problem but i would like to keep it sensible enough to not be a massive cost for initial set up.

Once i have all the advice i need and get it going, i plan to put up my box design plans in very great detail, in both AutoCAD format (for those who want to make alterations) and PDF format so if you like my design, you can copy it freely.

Thanks for time guys.

Kind regards,

Green Troll

Oh, and this is being done in the UK (just so you know)

Green Troll said:

Oh, and this is being done in the UK (just so you know)

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what size and cfm fan u got?
and doing a dry run is a excellant ideal

I am looking at a 4" exhaust with carbon filter (http://www.greenshorticulture.co.uk/categories/Growroom-Products/Fans-&-Fan-Filter-Deals/RUCK-Fan-&-Rhino-Pro-Filter-Packages/) that does around 285 m3 an hour. Now i am making a few alterations because i just happened to pick up a free-be of 3 sets of fluorescent strip lights (2 in each ballast) with the reflectors. These are only standard office type ones, 58w each strip light, producing around 39 lumens per watt, so around 13,500 additional lumens for my little lovelies. I am going to put these on the side walls of the veg box with the idea they will help them grow outwards a little more.
Again, this is all speculation and only from what i have read. Anyone care to comment on how good/bad/pointless fluorescents are for vegging?

Anyway this will increase the volume of the veg box only slightly, and with the new volume i have calculated (4.75 m3 total) it should take exactly 60 seconds for the air to cycle. I understand the entire volume should be cycled about every 5 minutes? I would use a small fan but this is the smallest they do and i suppose it doesnt hurt for my babies to get too much fresh air.

I am also currently waiting on some feedback from some second hand lights from someone who has stopped growing (friend of a friend) but i have no clue what size/wattage lights they will be. I am hoping not any more than 400w but i am guessing they are going to be 600-1000w as it is coming from a large farm. Can you downsize these by putting 250-400 watt bulbs in them without any modification to the ballast?

Also how is the moisture in a box with 40-60% humidity? Are my side lights likely to be in trouble? Should i waterproof them? If so, what is the best way to do this?

Many thanks to you guys for your advice.

Actually i am thinking i definitely will have to waterproof the side lights. Would perspex work as well as glass for light to travel through? I really dont fancy paying out for custom cut glass =)

I would do the fluoros in the veg cab (or a 250w MH) and a 600w HPS in the other side. Also go for a bigger fan, 6" and 400cfm. Remember, buy right, buy once. Don't make the newbie mistake of under-doing it and having to go and buy the right stuff later.
No, you can't put a smaller bulb in a standard ballast.
Humidity is fine.
Bad side to the 600/250 combo is it will cost in electric (about £1.75 a day)
Good side, you should be putting out at least an OZ a week when it's up and running. Go hydro and get everything right and you could be looking at 2.

Dont fancy hydro just yet, want some experience growing first.

The fluoros will be in addition to the 250w MH, not a replacement, so i am hoping they will help growth outwards as well as upwards.

And do you really think i need 600w HPS instead of 250w? For a single meter squared? I read that 250w is good for 3' x 3' (900mm x 900mm) and 600w for 12' x 12' (2.4m x 2.4m). I dont want to massively over do it if i dont need to. Or is it simply just to get massive bud? Electric cost isnt an issue with paying it, i just dont want it to raise any eyebrows with my sudden increase in usage.

And with the fans, is it wrong what i have read that the volume of the grow box should be cycled every 5 minutes? A 6" fan seems a fair bit industrial for less than 5 m3 of air to change. I dont want it sounding like a factory.

OK with further reading it seems that coverage is mostly aimed at vegging, and recommended for my area is about 400w for flowering. So would the 600 just make it flower more? This is also making me start to think i MUST put high quality reflective material on the flowering room for all this extra light to be spread around enough.

600w is more efficient watt for watt. I don't know why. It would make it flower more, but it's about the depth of penetration into the canopy (hence longer, fatter buds) more than anything.
Reflective material is a must. It's free light.
All i would say is a 600 costs about the same as a 400. Both would work in your area.
I know where you're at with the electric showing up. I have a pound meter now in my new house and have had to drop to a 250 hps. My pythons vivariums don't help.

thanks for the advice man, will defo look at getting a 250w + 600w set up now. As for the 6" fan, im gonna go for the 5" instead, and if it doesnt work, ill get another 5", those 6" are damn expensive heh. nearly twice the price for an extra inch.

any recommendations on reflective material?

Mylar is about the best for reflective or so I've read.

Yep, Mylar. I use Megalux megashield as we get helicopters around here and it's meant to mess the flir cameras up. Not sure how effective it is though.
Don't discount hydro. After all that work it's only about another £150 for a setup and all your nutes for a grow. You will get that back twice over on the first grow and it's not as complicated as it sounds. It actually takes a lot of the guesswork out of watering, nutes etc and cuts down on maintenance.
If you need any advice, p/m. me. I have always done similar sized grows.

Yeah, definitely going to look at it at some point, but just for now i want to soil grow it. I have someone with a lot of gardening background looking after my plants, and i dont want to confuse the old dear with hydro just yet =)

Sounds good on the megalux. Will have to source some of that. I have decided to cut the size of my rooms down back to 1m x 1m and cut windows in the sides for the Fluoros. I want to keep the inside as flush and uncluttered as possible. Not just for the light reflections, but for cleaning, access, etc etc. Have also decided to bite the bullet and use adjustable lights for height. I initially wanted to control the temp better by keeping them stationary and moving the plants to suit, but i think this will risk too much damage to the plants. Also because i had a look at some 1m square pot trays yesterday and i realised 5-9 plants would fit quite nicely and i dont fancy moving them all the time.

So that will be more trial and error looking at how the box heats up at various light heights. I think i will have to bodge something together with a heat sink and fan and draw that heat up straight towards the extractor fan. Has anyone seen this done? And which bit of the ballast/reflector gets heated up the most? I am guessing it is the top section closest to the bulb?

This has turned from an idea to grow a few plants to a small farm lol. Im getting excited =D

Green Troll said:

Yeah, definitely going to look at it at some point, but just for now i want to soil grow it. I have someone with a lot of gardening background looking after my plants, and i dont want to confuse the old dear with hydro just yet =)

Sounds good on the megalux. Will have to source some of that. I have decided to cut the size of my rooms down back to 1m x 1m and cut windows in the sides for the Fluoros. I want to keep the inside as flush and uncluttered as possible. Not just for the light reflections, but for cleaning, access, etc etc. Have also decided to bite the bullet and use adjustable lights for height. I initially wanted to control the temp better by keeping them stationary and moving the plants to suit, but i think this will risk too much damage to the plants. Also because i had a look at some 1m square pot trays yesterday and i realised 5-9 plants would fit quite nicely and i dont fancy moving them all the time.

So that will be more trial and error looking at how the box heats up at various light heights. I think i will have to bodge something together with a heat sink and fan and draw that heat up straight towards the extractor fan. Has anyone seen this done? And which bit of the ballast/reflector gets heated up the most? I am guessing it is the top section closest to the bulb?

This has turned from an idea to grow a few plants to a small farm lol. Im getting excited =D

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the ballast should be outside room and the light bulb and reflector get the hottest

Sorry was being a donut there putting ballast, i actually meant bracket/reflector heh. Tooooo much weed xD

I am thinking of gluing a CPU heatsink to the top of the reflector if temps get too high, and channeling the direction of hot air flow right towards the fan/filter out pipe. Anyone else done this and was there much success? I have had a browse of the forums but couldnt find anything.

Also what sort of plant count can i get in a 1m x 1m area? I am thinking either 5 plants (one in each corner and one in the middle like the 5 on a dice) or 9 plants, 3 by 3. Not sure if this would crowd them too much, but would 9 crowded plants yield more than 5 plants with space? Height wont be an issue, obviously, in a 2m tall box, being mid plants.

just get a aircooled hood

I'm not endorsing Megalux. I got it for peace of mind but am still not convinced. Maybe it works, maybe not. I really don't know. I don't own a helicopter or flir camera so can only optomistically trust the blurb.
In a 1m area I would be aiming at 4 indica plants. Just my choice though.
Listen to and befriend experienced growers (FAB etc) for advice and always take the status (i.e. veteran smoker etc) as a clue of who you are talking to. As I understand it, the number of green dots means nothing, it's just a signal of how many posts they have. (Often means they are kids/teenagers whom have got into long conversations about yo mamma etc). Remember there are a lot of haters and people who just plain don't know what they are on about on here.
If you are going to glue a heat-sink onto the reflector, look into the stuff they use for computer processors (thermal grease) or brake pads on cars (copper grease) and bear in mind where that heat is going to be dissapated to.
Best of luck.

yeah i used to do a lot of PC building so thats where the idea came from =D

thanks for all the help guys. how do i give you guys rep?

Green Troll said:

yeah i used to do a lot of PC building so thats where the idea came from =D

thanks for all the help guys. how do i give you guys rep?

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the star under their post
the thermalgrease will not secure a heat sink it is to insulate

and if u in usa dont even worry about flir or copters they cant use flir in usa without search warrant and if they got evidence to get that they wont use flir just kick door in and shot pets and family members
fucking pigs

im in england >_<