Amount of Fans to Keep Very Small Grow Box Cool (images)

I was wondering what kind of Fan I would need to keep a 400w HPS/MH bulb cool for a grow box around the size of
H: 24.4"
D: 15.7"
W: 21.7"

I know, I know, its too small... But its what I've got and I want to grow my own

I'm thinking
1 x fan for bulb
2 x fans for exhaust
1 x fan for isolating
w/carbon filters on all of them except the bulb.

What kinda fans(or CFM value) would I need to get to keep this in the weed growing region of 65-75?

(here's a picture of how I was thinking of doing it)


Also, for the tree I was thinking...

for this size a 250w is sufficient, a 65-75 fan good enough through the bulb in a cool tube is best way

just how many plants are you gonna try to fit into that space?? looking at those pix, it looks like four, am i correct on this??

zem said:

for this size a 250w is sufficient, a 65-75 fan good enough through the bulb in a cool tube is best way

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I was thinking the same however I kinda don't want to go that low considering I might want to upgrade to a bigger box depending on how much I like growing...
Is that a 65-75CFM? How hot do you think it'll get in the grow box?

racerboy71 said:

just how many plants are you gonna try to fit into that space?? looking at those pix, it looks like four, am i correct on this??

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Um well I'm going to try and fit 1/2 and grow them like a side ways SCROG or just a really weird LST grow...
Basically I'm thinking of having a guide wire/fencing behind the weed, then tie it to the guide wire so I can control where it grows..




I really don't know how much I'll be able to grow them out... I'm thinking I'll be able to grow them around the corners too? It should be an interesting experiment...


I might even try 3, with a setup like this... But I'll have to stump plant 2's growth somehow..

hmmm... problem with this box is that it will suck to stick a 400, will heat it up cuz of mainly the height, 3 ft barely and you have to fit pots, plant height and light with a distance from plants, might want to just make a right box for the 400? you will cut the work and trouble in 1/2, i'm just saying...

Can't really don't have enough cash, struggling to afford the lights... But slowing convincing myself that its worth it xD

But with enough exhaust fans I should be sweet thought, right?
If the bulb is the thing that creates the heat if I put a meaty fan on it to remove that heat everything should be alright... Hopefully..

yeah well if you really want to stick a 400 in there i guess you can pull it by getting a cooltube and making the whole base of the box as medium make it shallow and scrog must be able to raise light to the ceiling, yeah you can pull it, not the simplest and most efficient but feasible

i think you could pull it off great with a 250 if you scrogged it like you plan on doing so to make penetration no longer an issue.. but i do tend to agree that the height of your box is gonna be your main problem.. the rest of it looks good, but like someone else has said, pots, and distance from lamps, and your not gonna have much room in there for plants, even if scrogged on lst'ed..

Okay, so bottom unless I really want to piss around I need to get a bigger box.
Which means back to a 600w ballast.. ugh, what would be the worst/average/best yields I could get out of this method?
Would I still get okay buds? More light the better, right?

zem said:

yeah well if you really want to stick a 400 in there i guess you can pull it by getting a cooltube and making the whole base of the box as medium make it shallow and scrog must be able to raise light to the ceiling, yeah you can pull it, not the simplest and most efficient but feasible

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How shallow is shallow, I could raise the chest of drawers a little bit higher to allow for some more pot space...

I've actually got quite a few questions about fert, mediums and drainage options...

Millsie said:

Okay, so bottom unless I really want to piss around I need to get a bigger box.
Which means back to a 600w ballast.. ugh, what would be the worst/average/best yields I could get out of this method?
Would I still get okay buds? More light the better, right?

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more wattage isn't always a good thing tbh.. the added watts brings with it added heat, and in my eyes, added heat is more detrimental then the added lums would be beneficial, and what you would gain from lums, you would only loose to heat issues..
i was told not to get a 400 watter unless i had a 3 x 3 area to grow in as the added heat would kill me.. i barely have a 3 x 3 area, and he was sure right when i got the 400 watter.. i had to really beef up my ventilation as a result of the bigger watt's..
try and look up and see how much square footage a 600 can cover, i think its like 4 x 4, so unless you have near that amount of room, the added heat will just kill you in the long run..
you could always buy a smaller watt lamp and get a few cfl's or a t5, and would be better off imho.. you'd get the added lum's, minus the heat that you would get from that big ass lamp, win win...

Yes, you're right. However the main reason why I like the idea of MH/HPS so much is that its so easy and compact. Essientially two items provide the light (ballast and bulb) Which seems like a lot easier to manage then lots of different types of lights..

Plus I live in New Zealand so quality growing lights are quite hard to come by (and expensive!)

How much would it cost to set up some sort of grow box with CFLs and a T5?

shallow like 6" then another foot for the cranked scrogged plants then a foot for the light + distance from plants... you definitely need a cooltube... better yet, make a bigger box or downgrade for a 250w. oh right i said that befoe

Well since I'm growing around the corners of the box I should be sweet for the distance from the light... I'll just have to make sure that nothing comes too close to the bulb...

I don't want a pissy 250w ;D I'll almost half my lumen output.. Making upgrading to a bigger box almost impossible without buying a bigger HPS/MH setup

View attachment 1491035View attachment 1491036

Would the dimensions of 87 wide, 40 deep, 99 cms high be better? I might try and pick that up depending on how much it is...

the more light the better? maybe if you seal room use co2 and A/C to make use of all the lumens. simply a 400 is more than double than needed in that area except if you use co2 which adds a big cost and is not simple, and a good 250w is great lighting for your area already you have very high lumens for that space you insist on sticking it in i think it will be unnecessarily harder and more electric usage, any extra space will make it better so try getting it right sized, are you buying a box? where will it be placed?