New grow area, help me design; space allocation and infrastructure

[turnip brain]

Hi, first post here, I have been lurking, reading a ton and learning.

I have my beans, have soil cooking, and am ready to get started very soon.

The big thing I need to get done is create the grow space. I have a space 28" deep by x 42" wide x 86" high (I will need to build a sturdy shelf for the weight of the soil as a divider, so probably subtract 3" from total useable vertical.)

What I would like to do is set it up with 2 spaces, one above the other, the lower for fluorescent light, moms, clones and possibly beginning vegging, then the upper space for plant maturation and flowering. Seems I may need the option to switch light source from veg to flower in this larger space. I plan on a 400-600 HPS for flowering in the upper cabinet.

I'd like to experiment with scrogging and mainlining, and complete a grow at a time in the upper space while starting the next in the lower space.

So a few questions:

question #1: with those dimensions, how would you allocate vertical space? how high should I plan for the lower space and the upper maturation space? I want light isolation between upper and lower, so making this "shelf" adjustable in height would seem to be fickle. I'd prefer to just permanently build it at the correct location

Question #2 I figure I will need the right ventilation/cooling for that upper space when under HPS. Anyone have a simple recommendation about airflow for that kind of space? The ambient temps here are never very hot. In winter around 60F and summer 70F-75F max. I am thinking in building the infratructure, I'll plan for a main vent for the light hood itself, and probably a secondary just to bring new air in, and extra hot air exhaust with scrubber. Conveniently, I can vent in and out with zero runs of ducting, just right through the walls of the cabinet into the surrounding space. How do I calculate the needed CFM and vent diameter?

Question #3: Will the light hood ventilation also need to be scrubbed? It will vent back into the home living space.

Thanks!

 

[messn'n'gommin']

I use a 2'x4'x8' closet, but I don't have it divided. So, bearing that in mind:

1) You might find it easier to have a cab/dresser/box of some sort for moms/veg/clones. Some pc fans and fluoro's for it and dedicate your grow room for flowering. Otherwise, if you're sure you want to combine the two, you'll have to make doubly sure there are no light leaks from the veg section.

2)The following link will explain it much better than I could.
“Ventilation 101,” by redgreenry
https://www.icmag.com/ic/showthread.php?t=112862

3) Ideally you'll want positive pressure on a closed loop for your light and put the fan before the light, pushing through. If it's pulling, the smallest opening allows odor to escape the flower room.

hth

 

[turnip brain]

I use a 2'x4'x8' closet, but I don't have it divided. So, bearing that in mind:

1) You might find it easier to have a cab/dresser/box of some sort for moms/veg/clones. Some pc fans and fluoro's for it and dedicate your grow room for flowering. Otherwise, if you're sure you want to combine the two, you'll have to make doubly sure there are no light leaks from the veg section.

2)The following link will explain it much better than I could.
“Ventilation 101,” by redgreenry
https://www.icmag.com/ic/showthread.php?t=112862

3) Ideally you'll want positive pressure on a closed loop for your light and put the fan before the light, pushing through. If it's pulling, the smallest opening allows odor to escape the flower room.

hth

Yay a reply! Thanks

I have tried to make it through that vent 101 info, but I am not an engineer! The volume is quite small at about 59 cu ft, and it seems the easiest choice would be a 6" fan with speed control to dial down to where temps are in desirable range.


So yours is a 2x4' footprint? What light and ventilation do you run in there?

 

[turnip brain]

3) Ideally you'll want positive pressure on a closed loop for your light and put the fan before the light, pushing through. If it's pulling, the smallest opening allows odor to escape the flower room.

hth

Copy that. It was suggested on another forum though that I use a single fan pulling from passive intake through the space, the light and scrubber. makes sense to me, and hopefully would not require a second fan. I guess the possible problem is too much air exchange for the plants. What do you think?

 

[messn'n'gommin']

Yay a reply! Thanks

I have tried to make it through that vent 101 info, but I am not an engineer! The volume is quite small at about 59 cu ft, and it seems the easiest choice would be a 6" fan with speed control to dial down to where temps are in desirable range.


So yours is a 2x4' footprint? What light and ventilation do you run in there?

Can empathize! lol...Am an old HS drop-out!

You're probably better off to go with a 6" fan and a voltage regulator, but a powerful enough 4" fan would work too. Just less room for error.

There are aspects that may affect it (somewhat up or down), but the following chart is a good rough guide to go by.



I use two 250w CMH lamps and a 6" fan (Company rated for 605 CFM but I question that!) and a variac type voltage regulator turned down to about 60%-65%. I have a differential of about 5*F in winter and about 10*F in summer. (btw...Technically, my closet dimensions are 22"x52"x96" but it's close enough to 2'x4' for me.)

Copy that. It was suggested on another forum though that I use a single fan pulling from passive intake through the space, the light and scrubber. makes sense to me, and hopefully would not require a second fan. I guess the possible problem is too much air exchange for the plants. What do you think?

That is sound advice! And a 2 to 1 ratio of intake to exhaust ports, as well! (e.g. Two 6" holes for intake and one 6" hole for exhaust.) A lot of air flow isn't necessarily bad, but not necessarily good either! It can dry out your room and plants a lot faster!

A closed loop system for an air-cooled hood is intake>sealed hood>exhaust and is separate from room ventilation/filtering system, intake>filter>fan>exhaust and involves another fan. There are pic's of each system in the "Ventilation 101" thread.

BTW...I apologize for taking so long to respond! Peace, bro!

 

[turnip brain]

Hey, no worries, I really appreciate the response. I was thinking about this more yesterday and it seems like a single fan for the whole works may be a hard balancing act in terms of that airflow through the closet. It is very dry here, and excess air flow would definitely create dehydration. It would be much more controlled with a closed light vent and a second probably much smaller fan to circulate air into the space itself. For 59 cu ft, I think a 4" would be more than enough for needed air changes.

So, do you know, is the chart specifically about cfm through a sealed light system or is it about ventilation of the growing space?

 

[negative37dBA]

Your thinking in the right direction as far as dual exhaust goes. You can crank up the light exhaust to move heat but use a much smaller fan to keep a fresh air supply for the plants. it can get complicated though. You may want to go with a cool tube type design so it does not use much space and does not require sectioning off seperate parts for the light and the plants.