grow cabinet light/ heat questions

ginjawarrior said:

having spent a few weeks on here researching im nearly at the point of buying my equipment but just wanted to check it was right first

my grow space is a wardrobe
57cm x 92 cm x 168 cm high
that only leave me about .5 m2 canopy area (not enough)
so i plan on using a v shaped scrog which will nearly double the canopy area to .9m2
and using dwc for planting
im in the uk so ambient temps wont realy get above 20c (at least not till next year) and the wardrobe will be in a heavily ventilated room (top floor flat with windows open)

all good so far i think.
now about the lights, i would realy like to put in would be a 630w hps combi light in a home made hurrcane cool tube so that the light can be in the vshape rather than above it.
i found a cheap inline 4 inch fan that can move 107m3/hour
http://cgi.ebay.co.uk/ws/eBayISAPI....6&ih=026&category=122909&ssPageName=WDVW&rd=1
now using about 1/2 a meter of insulated duct to get to a homemade carbon filter ontop of the wardrobe would it be reasonable to guess that i'd have maybe 80m3/hour still traveling past the light?

would this be adequate to keep the buld cool enough A. to fit into this sized cab and B. allow light to get withing say 10 inches of plants?

i will have some small fans inside the cabinet to help flow through the canopy and was thinking about maybe a couple of computer fans in the roof of cab + filter to help with flow and for night time ventilation

would i need to remove humdity over the night time or would it be ok?

one last question would it damage the the hps to be run in a hurrcane cool tube without a fan running? say if fan was connected to a temp guage would the bulb over heat and self destruct?

any help or suggestions will be gratefully received and thanks in advance

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Nocturn3 said:

That fan will not pull through a carbon filter. I made the same mistake when I first started growing. You really need a centrifugal fan and a proper CF. I grow in a similar space with a 250, a 4" VK centrifugal fan and CF, and I can just about keep temps acceptable (i'm also in the UK).

I could run a 400 with cooltube, but a 600 would be overkill, without upgrading to at least a 5" centrifugal. As it is, i'm happy with the 250 for now, and at bang on 50w per square foot, it does the job.

My advice to you would be less money spent on lights, and more on extraction.

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Nocturn3 said:

These are the fans I use, and there's not much difference in price as they get larger. I recommend them, since they pull through a proper CF very well, with plenty of airflow left over. They are noisy , but there are ways to quieten them down to a manageable level.

When looking for a fan, there is more to it than cfm ratings. That is only one half of what you need to know. The ther number that isn't usually advertised is the static pressure rating, usually measured in pascals (Pa). This number rates how well the fan performs under pressure, like carbon filters, or bends in the ducting etc.

Axial fans, like the one you linked to, have very low static pressure ratings. Centrifugal fans have a high static pressure rating (although usually at the expense of more noise). You can also get "mixed mode" fans, that are sort of a compromise. They are quite powerful, but not too noisy. They don't have too much airflow after you add a carbon filter though, so you may wish to go for a couple of sizes bigger than you think you will need, if you get one of these. Google "vents TT fan" for one example of them. I haven't used one, so I can't vouch for their effectiveness.

I think a 5 inch centrifugal fan would be adequate for a 400 in your space, given sufficient intake. You could go for a 6 inch, and get a fan speed controller to turn it down, which would give you as much pull as the 5 inch, but with a lot less noise.

I can't say for certain whether you'd get away with a 600, since i'd only be guessing, but my instincts tell me it would probably be overkill.

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