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First Grow Box - Need advice!


New Member
Hello everybody!

I've been looking into growing for quite some time now since where I live weed is kinda hard to come by. So I did a bunch of research and keeping in mind that I want to keep this on a more budget kinda build I've now got most of this project planned. I've also read tons of guide on growing and I think I am ready to start growing some weed, but that part will be for another post :) Here is what my setup will look like:

Strain: Auto-flower Sensi Skunk Feminized
Grow Box dimensions: 60cm x 60cm x 120cm
Reflective material: flat white latex paint
Lights: 6 x 23w spiral CFL (138w total)
Outtake: 2 x 6cm 12v computer fans
Medium: Soil, BioBizz Light-Mix
Nutrients: BioBizz Grow, Flower and Top-max
Odor filter: Homemade with super activated charcoal

Grow Box:
The grow box will be custom made by me using MDF wood panels (120cm x 60cm x 1cm) and painted with a flat white latex paint on the inside. The panels will be glued and screwed to a previously made wooden frame. Every precaution will be made so that the box is light leak free and air tight. I've made an image to quickly illustrate the base layout:

As you can see the door will be in the front. The intake will be on the lower left side and covered with a dust filter. The outtake will be on the top right side of the box and will consist of 2 x 6cm computer fans blowing the air out into a custom made super activated charcoal filter. As for electrical I am thinking about sticking an extension chord with surge protector to the top back since I only need to power the lights and fans. All the electrical wiring will be plugged outside and the wires will go into the box trough a hole.

Next, we'll take a look at the inside of the box viewed from the front.

As you can see I've made a light fixture (illustrated below) that will hang from the top of the box by a chain so I change the height of the lights. My idea was to leave some space at the bottom so that I could slide a tray under a grid where the plants would be so that I could remove the excess water easier but might be tricky because of the door. Both intake and outtake will have a light trap to prevent light from getting in. I will also have a digital thermo hygrometer hooked on the outside with an external sensor on the inside of the box so i can check temp and humidity without having to open it.

Light fixture:

This is the light fixture that you can see hanging in the figure above. I was planning on putting a lamp in each corner with a 45 degree light socket facing the middle and 2 more lamps in the middle horizontally. All the wiring will be done on the other side of the fixture with a single wire leaving to a plug outside the box.

So this is what I got so far as grow box goes. Still, I have a few questions remaining:
- CFL light bulbs are kinda expensive in my country, hence why only 6 x 23w. I was wondering if I could get away with 2 plants with the 138w and 60x60x120 cm dimensions or should I just go for one? Keep in mind I am not looking for a crazy yield, just looking to get a taste at growing and learn while doing so and having something to smoke for myself later on.
- Can I run 4 x 6500k and 2 x 2700k for veg and vice versa for flowering or should I just keep it 6 x 6500k for veg and 6 x 2700k for flowering?
- Should I just pull all the lights on the light fixture horizontally?
- Should I keep the intake passive or add fans blowing air inside?
- Do I have to worry about odors leaving the box trough the intake? If so should I just cover it with an activated charcoal filter mesh instead of a dust filter?
- Will the 2 x 6cm fans be enough for outtake and keeping a decent airflow trough the box? I've read that's its all about how much CFM they can move but it says nothing on the fan.
- Should I worry about the electrical? If so what can I do to improve it.
- White paint or mylar? I chose white paint because it seemed easier for my first time

I think this is it for now guys! Feel free to give some advice or even your opinion on the matter! If any more questions arise I'll post them later.

Happy Smoking!


Well-Known Member
If CFL's are that much, consider picking up a Mars 300 from eBay. They're not that expensive and would be good for your space. If you can, try and get 150cm height at least, especially if you're putting a drain box under your plant.

I built my own grow box, same height. I really wish I'd gone up at least another foot.

I bought a role of Mylar for my box. I wish I'd done white paint. Easier and cheaper


New Member
Yeah i definitely agree with you on the white pain. Heard mylar is a pain in the ass to apply.

To be honest one of my biggest concerns is that somewhere down the line i'll come to the conclusion that its not tall enough. I am not sure as it is right now with the 2 x 6cm fans so adding the extra space definitely worries me and makes me feel like I have to add more fans. I figured i could train my plants to stay shorter and wider but that leads me to the same problem plants wise. If i sacrifice on height for width with 2 plans, the 60cm x 60cm might not be enough. From your grow journal I can see you had 2 plants on your first box. If you could go back would you have just done 1 plant or you feel the 2 had enough space to grow?

CFL are expensive yeah but not that much. My country sucks when it comes to order things online, and getting the MARS 300 will cost me around 150 euros while the cfl lamps will cost me around 50 euros. For my first grow I am not ready to drop that kind of money, but if everything goes well ill definitely look into it.


Well-Known Member
I would still do 2 plants in my space and height train, just in case one dies or some catastrophe happens at least I have something to continue on with, and I can supercrop to spread it out horizontally more.

I was paying $9 USD for each 45W CFL (150w equivalent), so $72USD just on CFL's, and a Mars 300 on EBay was around $80. Factor in the other materials for reflector, sockets, wiring, etc and the Mars 300 would have been about the same price. I can re-use the CFL's in my home, though.

I just did a quick look on EBay. A Mars 300 shipped to France is only about 70 Euro. It's their old, discontinued model, which is why you won't find it on the Mars Hydro website. There are UK sellers, as well, which would seriously cut down on shipping costs.


New Member
After some extensive seach I found this light with shipping costs comes around 60 euros

Mars 300 LED Grow Light Lamp Full Spectrum Veg Bloom for Medical Indoor Plants | eBay

I am definitely gonna get that, comes at the same price of the cfl + light fixture and it has more watts with the extra of putting out lower temps. Realy appreciate the input!

I would like to get some more advice tho. I read on your first journal that you had problems with temperatures and upgraded your fans. As my setup goes, I salvaged 2 x 6cm computer fans that I am thinking of using as outtake. Ive hooked both to an old 12v cell phone charger and they work pretty good and seem to blow out quite some air (cfm ration is missing on the fans so cant do the math). Still, with the lamps and size of the box plus the carbon filter I am not 100% sure they'll do the job. Would it help to add 2 more computer fans on the intake to help push air in? Or just spend the money on better fans?

I've also read auto-flowering strains aren't very good for first timers because the veg state is so short it doesn't give time for the plant to recover if something goes wrong. So should I start with a regular strain and have control of when to go flowering so that I can LST my plant into being more flat or just even so for the sake of something went wrong (first time so thats a for sure)? Or just stick with auto-flowering?


Well-Known Member
Remember that when it says 300W LED, it's probably only running at 150W. I always divide listed LED wattage by 2, because LED's never get driven at full power.

Most of my problems had to do with running 330W of LED in a small space. My Mars R96 only pulls 210W, although 96x5W LED's could be driven much higher. The lower wattage reduced my temperatures quite a lot, but running an inline fan definitely did help, too. My intake was pretty basic - a couple of 2" diameter holes. When I want to reduce air intake, I stuff a rag into one of them or both of them.

I'm not sure what carbon filter you are using, but that is one thing that I would also spend good money on, especially if stealth is important.

I'm not entirely sold on autos. I like photos because I can flip them when I want, and get them flowering when I need to. I just did a grow with 2 autos, and expected them to finish at the same time. They didn't. They didn't even start flowering at the same time. I was entirely at the mercy of the plant instead of the other way around. I'm going to finish growing my auto seeds that I've picked up, but from now on, it's just going to be photo plants for me.

As for computer fans. I love them! I use them all over my cabinet/growbox for circulating air.

I like to get a single 12v power supply, like this one:

72W 12V 6.3A Constant Voltage LED Power Supply - White + Silver Grey - Free Shipping - DealExtreme

and some 2.1mm Jacks like these (to splice to the computer fan wires and to the power supply):

10PCS/Lot DC Male Power Connector Cable Adapter Jack Pigtail Plug Wire Cord 5.5 X 2.1mm Plug Wire For CCTV Camera-in Connectors from Home Improvement on Aliexpress.com | Alibaba Group

a splitter:

High Quality DC Splitter Cable CCTV Security Camera 2.1mm 1 to 4 Port power extension cord Cable 12V DC Electronic Accessories-in Power Cords & Extension Cords from Home Improvement on Aliexpress.com | Alibaba Group

and then I can run a whole bunch of computer fans from a single power supply. You can even get 2.1mm extensions so you can easily run wires all over your cabinet/tent to get fans where you want them and the cables are more nicely bundled.


New Member
Thank you so much for all the advice man! I think i have everything figured out as of now just waiting on confirmation for a place to set my grow box and Ill run to the supply store. Ill keep you posted with updates as much as can in hope to get some input from you and give your opinion on how my plants are looking :)

Wish you the best of luck with your grow

Take care

Dwight Monk

420 Support
420 Staff
I have two boxes I built, you can see them in my Anti Journal Journal link. One is 4 foot tall and one is 6 foot tall (I'll let you convert that to cm, silly Americans measurements ;) ). I'm using 4 small computer fans (2 inlet and 2 exhaust) and far as I can tell it is plenty of air movement, or I got finished product out of them so may not be ideal but it works. I just wired them all together so only have to use one 12v adapter, found one at Goodwill for 2nd box that has 4 voltage settings so I can actually slow fans down on that one if I want but haven't done that as of yet.


New Member
A few thoughts about your fans,
Is it possible to put your outtake fans straight up out the top, instead of on a side? If so, then you would want an intake on both sides, towards the bottom as you've designed. This will help pull all the heat out. I also feel you may end up wanting at third or even fourth fan, depending on how warm it gets in there. Perhaps just leave some room for more if you discover they are needed. Computer fans are hard to guage as they have a wide variety of performance.
I absolutely love 415friendly's power suggestion...gotta get one of those myself now.


New Member
Yeah I've changed my design quite a lot already. I am taking 123D advice and putting 2 fans on top on both sides pulling air out and one intake on each side at the bottom. I might use some really old pc fans for the intake (they don't move that much air). As for exhaust, friend of mine happened to have 2 x 12cm fans laying around so he said I could have them no problem, they are rated at 69 CFM so i think 2 should be more than enough to keep it cool especially with the LED panel. As for my remaining pc fans I think I'll just use them inside the box blowing air at the plants.

As for my odor filter I've got a pretty good design worked out and with the extra fan power I am pretty sure air will have no problem going trough. It will be made with granulated super activated charcoal for fish tanks with some wire mesh and stockings (might post a DIY if it ends up pretty). I've looked online and it seems they work pretty good! Since I am only growing 2 plants and the grow box will be setup in a attic kinda space on the top floor of a building, I am not too worried about smell.

And yeah I totally missed what you said about the Wattage on the LED panel. I did see true wattage was at 150W but from what I've read its pretty good for 2 plants in a 2"x"2 area. It's still worth for me since I would be at 138W with the CFL for around the same cost, not to mention the LED panel is easier on the temp so this is a must.


New Member
Excellent Joao. Yes I think with those larger fans, and an LED panel instead of CFL...just two exhaust fans should be plenty. But still, knowing where you would put a third just in case is a good consideration. The smaller internal fans should focus more on 'fluffing' the plants than being for intake.

Your odor filter does sound cool. Can't wait to see some pictures.
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