Advice needed for cab modifications

Hey guys,

I've always found this site a great source of advice and I require a little help with the grow box I'm putting together.

I'm converting a cabinet and I'll be doing all the adjustments to it over the next week- I was going to use a 6inch extraction fan and carbon filter- but after purchasing these I feel that solving my odour issues has created a new problem with noise.

Light- 300w LED.
Medium - soil.
Grow Box will be a converted wooden cabinet.
Plants - White Widow and Hindu Skunk.
Height - 1600mm
Width - 850mm
Depth - 420mm

I was after some suggestions as to weather I could get away with less fans and no carbon filter? I considered having just one outward facing fan at the top of the box and vents at the bottom of the box?

Obviously this will determine where I can keep the set up- both indoor and outdoor (undercover) are available options- but indoors with a 6inch extraction fan and 4 inch intake fan is real noisy, the outdoor alternative means I'll need to lightproof it while ensuring adequate ventilation.

Any advice would be very much appreciated as I'm keen to start making the necessary adjustments and I need to make a decision which way I'll be going with this.

Can provide pics in a couple of hours if that helps.

Thanks in advance guys!!

Yes, a simple exhaust fan and intake vents [negative air pressure] is exactly what you want. But make sure your interior air keeps moving. I use [2x] 120mm fans in my box. [Dimensions are 90cm Tall x 69cmWide x 50cm. ]

Passive intake should be 2x the surface area of your exhaust. Try and keep temp between 23-26C is probably ideal, but I manage 20-28C and do okay. 35-55% relative humidity is good but may go up or down 15% which isn't terrible.

Cheers for the reply....

I kinda thought I went a little overboard with the fans but I guess not....

Any chance I could get rid of the intake fan and just use additional passive vents or is the 4 inch intake necessary?

Will post pics of cab soon.

Cheers

Yep, an intake fan isn't really that necessary and more vents are PROBABLY required, but you have to mess around with the tempature and humidity for a final go.



Post pics!

Yeah I'll put up some pics in the next 24hrs or so.... Just finalising plans as I'll start modifying the cab this week.

But hypothetically, if I wasn't using a carbon filter, then I wouldn't need to make the cabinet quite as airtight- so with enough passive vents would the plants get enough air?

im just looking into possible alternative before I start making irreversible modifications to the cabinet.

All of my cabs, before and after incorporate the same design.

Active exhaust[powered fan] located in the highest spot possible to vent as much hot air as possible. A passive intake [vents] in the lowest spot possible for colder air intake but located [hopefully] opposite the side of the exhaust.

Inside I breeze interior air with supplemental fans just enough to blow the girls around continuously [small pc fans].

You are not bringing in air as much as you are bringing in new CO2 for the plant. I seal mine for maximum efficiency, just the same as any other. Leaks are the bane of the cabinet.

I recommend 5-10 room changes per minutes depending on your measurements. So calculate your total cubic cm3 and multiply by 5-10. This is what the fan should be capable of with the correct intake surface area [2x]. [Well below 100cfm and this is where even the smallest 4" fans are too big WITHOUT BEING ADJUSTABLE]

This is all without a filter, mainly because I don't use filters either. But I leave my fan's adjustable, just in case I do. So I have DIY fan regulators for turning fans up or down.

Takes a few grows to start thinking of things that makes sense....adjustable fans took me 3 times. Interior fans, twice before I realized I needed them....

You're right, I've got my work cut out for me....

Great explanations about everything too mate, very helpful indeed.

I was kinda hoping to avoid adjustable fans for the time being. I figured the current intake could just kick in for 20min or so every few hours- but you reckon adjustable settings is the better way to go.....

Fucking fans, I spend way to much time thinking about this!

I am just trying to save you some of the hassle.


I use 12v PC Fans, all of them. My "adjustable" control is a 1K linear potentiometer for about $1.50US....with LED's the heat reduced even over cfl's is night and day. My 3.6 cu foot cabinet is being vented by a 90mm Fan @ 5v's. heehee......

I do use timers too, usually I run fans at night. but I do on off periods throughout the night to keep humidity down. [ONLY Using timers is fine for controlling the fan too]
Sorry for long rant....

Nah it's good.....

I'm re-evaluating it all now as you've given me a lot to think about.....


Leaning more towards ditching the filter now which will free up heaps of space inside....

Pics of a toy box I knocked up just for fun.

Very amateur this- it glows in the dark and the ventilation isn't good enough to keep it closed up 24/7- not exactly stealth!!

But as you said, you're not going to ace it first time around, you learn from your mistakes....

^very healthy!!!

Cheers mate

More of an experiment than anything else- I cut a lot of corners while making it and had to improvise as I didn't really have the necessary tools- so yeah i'm curious to see what the end result could be when a bit more effort and care is used.

Anyways bro, is it cool if I maybe run the plans for it all by you before I start hacking into the purposely bought cabinet? I tend to over think things and an experienced second opinion wouldnt go astray.

I appreciate your input so far!!