First grow ventilation question :) thanks for any help :D

hi

my cab is going to be 80*50*150cm approx which is about 20CF. plan to make homemade carbon filters using these 120mm fans. Max. airflow:80CFM

Am i right to assume that when the carbon is added we can assume that max airflow is less than half, say 30CFM?

If so would 2 such fans provide enough extraction power for the size of cab i have?

thanks for anyone who answers its my first grow and there is a lot of different information out there

A carbon filter is normally made so that there isnt so much resistance because of the massive surface area of intake, it would reduce it somewhat but not half. One that is home made should have the same design...

ah ok thanks

so if my cab is 20CF what CF/M is the minimum i should aim for?

i guess a bit more background is in order - and some numbered questions (numbering things is fun)

my brother has lent me some stuff he isn't using, couple of vegging CFLs and reflectors and a 400w ballast and reflector and also i think a 120mm and an 80mm inline extractors i will go and collect once i get my car back (he wants to finish his phd with no distractions i think!).

i know my #1 enemy will be heat with such a tiny box, everyone who I've asked who grows says this (this is one of the few things that everyone who grows seems to agree on - quite a surprise when nearly all advice is so different )

1) one solution i was thinking about was just putting a new 200/250w bulb and using that with the 400w ballast? would this be possible? would i be able to buy a surge protector that would work in this situation? i don't know anything about electronics, is there maybe a better forum to ask this in?

pretty sure however that i am going to go with the 400w and just try to deal with the heat from the get go. its such a small space that i think i need to maximize the output and see if i can deal with the heat. idealy want to use the box as a full time flower box that i stick a couple of cuttings in every 10 days and have a perpetual harvest from

i was thinking that if i used 2 or 3 of the homemade filters in the my post plus the 120mm inline fan with a tiny bit of venting and a shop bought filter that should have a reasonable chance of keeping a box this size (about 20CF) cool?

2) so has anyone used a 400w in such a small space effectively? is there some kind of output to box size formula that would give me an idea of what the minimum amount of ventilation needed specifically to keep the box from getting too hot? i fear that CFLs will be really expensive to get the same light as a 400w...

3) should i just bite the bullet and get an air cooled reflector? just seems i could get much more suction for my £85 out 3 of the homemade carbon filters...

can anyone help a noob? ive already been told to use a 400w light with the ballast and not fool around in that area, but ive looked over the forums and i cant find a formula for heat dissipation from specific sizes of box or anything and help would be awesome

bumpybump

I think you need to bite the bullet and buy a a/c reflector, you can still use you carbon filter and with the reflector you will be able to move more heat with less airflow. Basically the amount of cfms you need is dependent on how effecient your cooling setup is. To cool this space I would suggest a min of 150 cfm for a aircooled reflector setup and as much as 300cfms or more for a open fixture. But a word to the wise aim bigger then you need, a fan controller is cheap and much better then buying a fan then learning you cant add any lights or grow in the summer.