My DIY Grow-Box Design; How's it look?

I've attached some pictures of to-scale plans I've come up with for a grow box I may make in the future (made with Google Sketch-Up 7). I'm looking for some general feedback, criticism or advice that some more experienced growers may be able to provide. I've grown before indoors in soil with good results, but not in an enclosed space.

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First, I'll explain the pictures:

Picture 1: The entire grow cabinet from the outside front with door open. Note that the main center chamber is lined with a reflective material (mylar or better, no foil). The door is lined with rubber weather stripping where appropriate to make an air-tight seal.

Picture 2: Close-up of the top portion of the cabinet, with some items labelled. Note that the black lines going straight up from the cooltube are just meant to represent strings for hanging, while the rest of the black lines represent appropriate-sized ducting between the parts. Note that air is being drawn up into the top compartment via suction from the filter caused by the inline fan, which is then exhausted out the back. Air intake for the top chamber is through two holes; One 6" diameter with ducting going to the cooltube (with the cooltube intake being ducted to the top left wall of the main chamber) and one 2" hole non-ducted at the top of the main chamber (for general ventilation of the cabinet).

Picture 3: Close-up of the bottom part of the cabinet. Note the 2" diameter hole bottom back center of the cabinet; This is the air intake for ventilating the cab (with the cooltube being vented separately with ducting). It will have a PVC elbow pointed down, spraypainted black inside for light reduction and with a carbon sheet over the end to act as a prefilter for the cabinet (a similar prefilter will be added over the 6" ducted intake for the cooltube as well). The screen (for ScrOG) and two half-width boards with cut-out are removable. The two half-width boards are there to provide a reflective surface underneath the plants, to provide an easy base for training the plants and to possibly place upward-facing supplemental LED grow light panels. The cut-out portion in these boards are for the plants to grow up through (there will only be two large plants in this cabinet) and are cut in a U shape to the end of the board so that they can be removed even after the plant has grown up through it (as apposed to if I just had a hole) to make watering and such easier.


General notes on the cabinet design:

I will be growing just two plants to a fairly large size in this cabinet (which measures about 2' x 3' x 7'). This box will be my veg chamber, flowering chamber and drying room all in one (no multiple chambers, which means less harvests per year, but thats okay with me as it's just for personal use).

I will be growing them in 5 gallon or larger pots of soil (I don't want to mess around with hydro yet, if at all). I have experience growing in soil with good results, and prefer the taste of some good organic soil-grown to anything else. I'd like larger than 5 gallon if possible but they seem to be hard to find any larger.

I will be training the main stem to grow sideways underneath the screen (along the wider portion towards each other but evenly spaced apart of course). I will then allow the main stem to grow back upward when it reaches the end of the screen, or cut off the main growing top at that point. This is to maximize the room for side-branches to fully develop (they get to go up through the screen) and even out the canopy on top. I expect to end up with a bit of a double-stadium effect in the end due to having longer growth near the plant base, but keeping things mostly even by training these longer branches to the sides of the cabinet where it'll be okay to have taller colas (since they wont be blocking others). I've never grown a plant sideways in this fashion, but have done LST and topping of plants to good effect before and the concept is pretty much the same.

I will be using a 400w light (digital ballast, MH in veg HPS in flower) with a 6" cooltube ducted as the pictures illustrate. The top chamber is basically a negative-pressure box to exhaust/filter air from the cooltube and main chamber (less airflow through the main chamber though with 2" holes rather than 6", to make sure most of the venting is where it's needed but still provide air exchange in the grow chamber and air filtration to keep smell down). I may also provide supplemental lighting with LED grow panels, facing upward from underneath the plants to help the low-growth thrive rather than die off.

A digitally adjustable humidifier/air purifier will be in the bottom of the cabinet between the two soil pots, near the air intake for the main chamber. This will keep my humidity at just the right levels and help keep my chamber free of contamination.

My electronics will all be housed in the top compartment of the cabinet where the fan, filter and exhaust are. There's plenty of extra room in there to put stuff, it'll keep the heat from such devices out of the main chamber, It wont be sitting outside of the cabinet (stealth is a priority), and I won't have to worry about spilling any water on the electronics.

I will have a small oscillating fan near the top of the grow chamber pointing down for general air circulation around the plants. I have personally noticed the difference in stem development (thickness and strength in particular) between plants with no direct airflow and those with (blowing them around slightly). I like strong stems.


Questions / Concerns:

As mentioned, I have never done a grow in a completely enclosed situation before, so I'm treading some fairly new ground here personally. Here are some questions and concerns I have:

Will the ventilation be adequate? - I am going with a good brandname fan designed to be used with those classic can-type air filters, rated at about 200cfm. Basing off my previous experience, I believe this should be adequate, but am not certain. In fact, I'm planning on running the fan at a low speed with a fan controller to reduce sound (along with other noise-reducing tips I learned such as suspending the fan with bungee cords and/or providing padding around it). With the ducted cooltube for the light and the fact that it's only a single 400w, I'm guessing it should be adequate. I can always adjust the fan higher if needed. Where I live, a little extra heat in the house is a good thing most of the year, and I'll have an AC in the room the brief part of summer where it's actually warm outside.

Will the ventilation, specifically in the grow chamber, be too much or too little? - The majority of the venting will be through the cooltube, but there are still the 2" holes for venting the main cabinet. This is to reduce radiant heat buildup in the cabinet and provide fresh-air circulation (no CO2 supplementation), as well as actually filter the air from the grow chamber. Will I be providing enough fresh air to my plants? Will I be providing more air circulation to them than necessary, overworking my air filter and humidifier? Are the intake for my cooltube and the exhaust too close together? (note regarding the last question, that I plan on having an oscillating fan sitting on top of the cabinet to blow air from the cabinet exhaust around the room).

Is growing them sideways under the screen and having the sidebranches become mini main stems too unusual to work? I've heard of plenty of things similar to this being done with great success, but not exactly as I am planning. Of particular concern is when I should switch from veg to flowering with the space I have given and the unusual growing method I'm using. Also, should I cut off the main growing tip when it reaches the end of the cabinet or should I let it grow up through the screen at that point?

Is there any downside to having them in a 5 gallon or larger pot their entire life? I'm thinking this would be beneficial as it would avoid stress from transplanting from smaller to larger pots as they get bigger, and I wont have any space-related issues since I'll only ever have two plants at a time anyway. I plan on using feminized seeds as I don't have a source for clones available (I've had good success with feminized seeds anyway).

How much benefit will a single or couple of LED grow panels pointing up at the plants from below give me? Also, if I do use supplemental LED lights, would it be worth it to invest in high-quality MH/HPS bulbs as well or would standard cheap ones be good enough? I'm familiar with the concept of light penetration through the canopy, and a 400w light is the smallest I've worked with so far. I'm expecting that without some supplemental light reaching the bottom of the plants, that I will see most of the lower leaves die off. I've seen this happen even with a 1000w light in a larger growing room, but then again I didn't have a cooltube and the light was 2' to 3' away from the plants. I'm expecting to be able to bring the light quite close to the plants using a cooltube (and it being only 400w).

As a bit of a side question, the Lumatek digital ballast I'm looking at says it works with both MH and HPS lights. So, to any Lumatek (or digital ballasts in general) owners, does this mean I just screw in either type of bulb and it works automatically? Do I have to adjust anything on the ballast, or do any sort of tricky wiring? I don't want to have any bulbs explode on me due to ignorance. As a sidenote to that question, would having a cooltube reduce/eliminate fire risks from exploding bulbs or not at all?

EDIT: One more question I thought of for those of you out there who use a screen in their grow (ScroG). Would it be worth it to have a second screen further up, to help support the plants and keep them where they're supposed to be? I'm strongly considering this option but am unsure if there are any downsides I should be aware of (blocking of the light would be my main concern, but it should be minimal).


Closing remarks:

Thanks for reading my monster post here, and hope you like my pictures and design. I expect most of the questions I have can only be answered through testing, but thanks in advance for any advice given. All I'm looking for is advice and suggestions regarding the design, so anything in general about it that you'd do differently feel free to share. I wanted to get the unofficial 'seal of approval' from you guys before I went ahead and actually made anything. Note that I may not be able to actually build this cabinet for an unknown amount of time (I may be moving sooner or later, waiting until then). If/when I do, I'll keep you guys updated, but don't expect to see real pictures of it too soon.

Oh, and I'm new here by the way, so hi everyone! I used to be an avid Overgrow lurker back in the day, but GC seems like pretty much the same thing, so here I am.

 

Definitely something I'm taking into consideration, and we'll see how it goes when it comes time to it. If needed, adding more holes or making a larger one isn't a big deal.

Did you happen to read the part about the 6" cooltube with it's own 6" ducted air intake? Also, I'll likely be running the fan at a reduced speed (the lowest speed needed to provide adequate temperature control).

Basically I'm trying to have a reduced airflow through the main cab (to increase the life of my filter and improve the effectiveness of the humidifier) which is facilitated by the use of the cooltube with it's own separate airflow system (does not draw air from the cab into the cooltube, but from outside of it). However, I'll have to balance this with the amount of radiant heat buildup (heat which escapes the cooltube into the main cab in the form of light) that will occur in the main cab.

Glad to hear you like my design. I'm the sort of person who will research things for hours before actually getting into it, to make sure everythings right the first time. A bit of personal experience goes a long way, too.

However, I likely wont be able to start building or using this design any time too soon. We're (my wife and I) looking to move into a house, and I'd much prefer to wait until after that to go ahead with my little project. I just figured I'd post my design and see what you all thought in the meantime, to make sure I'm not missing anything vital or to find ways to improve the design.

 

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Just looking for some feedback. I know there's alot of text there but you can just take a look at the pictures and you'll get the idea.

 

DoWorkSon:
Yeah that looks pretty similar. If it's the same setup as in your journal it's quite similar. In that case, here's a few questions for you:

1) What are the dimensions of your cabinet and/or grow space?
2) How much do you harvest per crop?
3) Any ventilation issues you think I might encounter?

Thanks for your feedback and something to use for comparison.

 

emrandel - Thanks for the detailed reply regarding my questions, they have been most helpful. I'll elaborate a bit on a few of the items you mentioned:

Regarding the ventilation, the single fan I mentioned is doing the ventilation for both the main cab (grow area) and the cooltube. It's doing it through one 6" ducted hole and one 2" non-ducted hole, both which lead into the top chamber. The fan pulls air through the filter and out the back of the cabinet from the top chamber. The majority of the airflow is going to be coming from the 6" ducted cooltube, since the hole is bigger and has a shorter path to go. My main curiosity lies in whether the 6" to 2" ratio (cooltube/cab ventilation) will work out to be the best (just the right amount of airflow through the main grow area).

Regarding the screen training, most of the times I've seen pictures of people doing this they do it with a topped plant growing up or one that's tied up to grow low. Mine are going to be growing 'sideways' in a straight line under the screen (lengthwise along the width of the cabinet). The main stem anyway, with the side branches going up etc. To me (and you seem to agree with me) this should work just the same as any other LST that's been done, I've just never seen it done exactly the way I intend to (it probably has just not known to me) so I wanted to run it by you guys first.

Regarding the LED's, I'm a bit on the fence about them as well. I've seen them (real life) work well for vegging, even the cheaper panel ones for $140 or whatever. From what I've read, they are currently no good for flowering and generally have a poorer light penetration (works worse the bigger the plants). My thought was that they might make decent supplemental lighting during flowering, especially if I skimped out and bought cheaper MH and HPS bulbs (since they will have a poorer color spectrum). I can appreciate the fact that some good CFL's could do just as good or better and be cheaper, but I like how very little heat those LED panels give off. I've seen some really good looking plants vegging under LED. Of course, on the flipside of that, said person using LED's does not use them during flowering. So I'm still not sure about using supplemental LED lighting, but I don't want to cook my plants or risk fire either (especially with my plan to have these lights underneath the plants).

I'll look into getting a Quantam ballast, thanks for the info (just what I'm looking for, some good advice from someone who's been through it already). What attracted me to the digital ballasts mostly is the (according to them anyway) lower heat emissions and higher light output, oh and the smaller size. The idea of it running a MH or HPS bulb without any hassle definitely won me over, as I wanted to try and avoid having to screw around switching them and then store the unused ballast etc. I was considering a conversion bulb but haven't heard many good things about those (plus they are very expensive).

As for the soil containers, I'll start them off with the tried-and-true red cup method (works fine for me) instead then. Do you think going from the cup to the 5 gallon pot would be too much? Maybe throw a 3 gallon pot inbetween or something, not sure. I've done it that way before (cup to 3 gallon to 5 gallon) and it worked fine but you can definitely tell the stress on the plant when transplanting. Plus with the screen and all and the plant growing sideways it might get tricky. Yeah I think I'll go from the cup right to the 5 gallon to save that bit of trouble in this case.

Lastly, I'll hold off on the second screen idea as well. If later it seems it might help them stand upright I'll consider it but I should wait to see if it'd even be necessary.

Regarding supercropping, I've heard several different depictions of what people call 'supercropping'. In the context of using ScroG (the screen part in particular) I'm not sure what you mean, but I'm guessing that a quick search on the forum could get that answer easily enough for me. If you feel like doing so you can post a link, but I'm pretty handy at finding info I need. I'll be sure to look it up. I've heard of screen related tips like pulling stems down through the screen a bit if they're getting too tall, or going for a graduated (stadium) canopy which forms a bowl shape. I've never used a screen as such myself so it'll be a first for me.

Thanks again for your reply, you've definitely gotten me some good answers and now you've got me thinking and obsessing about it some more.. It should be a fun little experiment to be sure when it comes time to it.

EDIT: I did some thinking and I came up with another question in response to what you said here:

That's not unusual at all. It's just LST, low stress training. Very common in fact for people with plant count/space limitations. Don't trim the main shoot, it's not the main shoot anymore. All the hormones have been redistributed when you make the original main stem horizontal. All side branches going up are now main branches, as far as the plant is concerned.

Would this mean that once I bend the main stem down to grow sideways, it will in fact stop growing that stem and instead just grow the side branches (now being new main stems)? I could imagine it would grow slower for sure but will it just stop, and I'm thinking about it the wrong way? The only training methods I've used before would be topping and a bit of stringwork to support the plants to stand up. Hmm, now you've got me thinking some more... If this were the case maybe it would work to grow it sideways but with a slightly upward slope as it goes, in hopes that it might continue to put more effort in growing the original main stem. Or maybe I'm wrong again with this assumption and it'll grow fine regardless. Or even another idea, I could grow it upward to the desired height (soon to be width) and then tie a small weight to the top and slowly train it to 'lay down' under the screen. Oh the many questions I have.. It keeps me interested for sure.

 

Thanks for the info. Good to see some actual yields off of a 400 watter. Up till now I've only used a 1000w for flowering, but seeing as it's going to be in a small enclosure now I didn't want that much light (or heat, rather). Are you still using the Master Kush x White Rhino strain? Definitely sounds like an interesting mix, I've considered getting the WR before myself. Did you make that cross yourself or get a clone? or did you just do the seedbank route as I do?

My cab should be pretty airtight if not completely, especially since I want it to be light-proof as well (so if I see any light, I'll know it's not airtight either). I'll be running the exhaust fan 24/7 anyway so any small gaps there might be shouldn't end up being a smelly problem. My air intakes are through a 2" and 6" hole, with the exhaust being through a 4". I've heard recommended before to have a 2:1 ratio of intake/exhaust, so I tried to stick to that when I came up with those numbers. I can adjust later as necessary anyway.

Are those numbers you gave for temperature difference in Ferenheit or Celcius?

Thanks again for your help and feedback. I've read through your grow journal and it's definitely a good source to use for comparison. Looks like you know how to grow some healthy looking plants for sure. Glad to know it can be done in a small space with relative ease.