Two Stage Venting..

[purpLEsmoke]

Greetings brothers & sisters

I am new to the indoor scene due to being suppressed from growing for a couple of years. I have however been researching as much as can & unfortunately i am struggling to understand everything in the Ventilation 101 Sticky. I am very excited to start my grow, i have been jizzing of the thoughts for ages.

Setup :

Preferably 3 x 3 x 6 FT
Using 600w Electronic with Super Sun 2

What confuses me is the calculating how much more cfm you need to add when u have ducting, filters etc?

For the light part [FONT=Arial, Helvetica, sans-serif]

LIGHTING CFM = 3.16*(Total Watts)/deltaT
where deltaT = 20 to 30 *F[/FONT]

So if my outside temp is ( 70 F ) 3.16 x ( 600 watt )/ 70 = 27 CFM ? so i only need 27 CFM to cool my 600w down?

All i need is somebody to help me grasp the basic concept of calculating all of the cfm requirements, I am not sure what the best height will be for my Super Sun 2 in a 3 x 3 DIY Tent although if i make it 6 ft the total of my 3 x 3 x 6 tent will be 54cuft. Should i compensate for the area that the Super Sun 2 is taking up ?

I am a little lost but im confident i can get there. Any help even referring me to other posts will be kindly appreciated & i hope with the information i acquire i can give back to the community & help other people grow. Respect to you all.

 

[Hydro-Soil]

It's a sticky at the top of this sub-forum.

https://www.icmag.com/ic/showthread.php?t=112862

Stay Safe!

 

[messn'n'gommin']

The delta T is the difference between the temperature of the air coming into the closed loop and the temperature of the air being exhausted. e.g. The ambient air temperature is 70*F and you want the light's exhaust temp 90*F. Then the delta T is 20*F.

The equation would look like this: (3.16 X 600w) divided by 20*F = 94.8 CFM (for delta T of 30*F it comes out to 63.2 CFM).

Were it me (note: I have never used a closed loop system), I would get a 4" 100-150 (or higher!) CFM fan and use it to push through. In a closed loop situation you want positive pressure. Any air leaks will be into the grow area as opposed to drawing stinky air through those leaks.

I see you have two windows in the room you're using to grow. If that's the case, I suggest you draw pre-filtered air from the window that is upwind of the other and then exhaust out the other that is downwind. It will save you a lot on AC/heating bills!

hth

 

[purpLEsmoke]

Thanks man, i got that now, delta T is the difference between the air being extracted in and the air being pushed out, so if delta T is 20F then a 100 CFM should be sufficient although we want to cool down the light even more, so would you say a 200 - 300 cfm would be overkill just for the light ?

As for the windows i will have them both available, so if im getting you right here you mean i should use the right window ( B ) to draw in air through a filter of some sort using a extractor fan ? then just use the left window ( A ) for the extraction ? does make alot of sense. I would also rather put one big filter on the window instead of these little filters on the tent, would pose less risk of getting pollinated & infected etc.

Hope i understood you correctly there man.

I am not hesitant to buy fans and extractors, i know that ventilation is key to having success in your room. I just want make sure i dont buy overkill & i dont buy anything that wont do that job, i have already invested about over 1000$ on this setup, super sun 2 350$ , 600 wat electronic ballast 400-450 $ & bulbs go for like 80 $, shits pricey here where i live but all i need to get now are my fans, Nutes, Ph Meter,TDS & hygrometer.

Really appreciate the help.

 

[purpLEsmoke]

I have found a inline centrifugal blower that has a optional humidity sensor & is fully metal compared to the other ones i have found. Price is also in the same range.

http://www.xpelair.co.uk/xid150.html

Its rated at 0.17 m3/s at 0 Pa. 0.17 m3/s = 612 m3/h x 0.588 = 360 CFM.

At 100Pa it is rated at 255 CFM.
At 200Pa it is rated at 150 CFM.
At 300Pa it is rated at 72 CFM.

From what i know the Pa has to do with the Static Pressure if im correct? this is how basically how much pulling power the fan has ?

 

[messn'n'gommin']

Again, I have no experience with a closed loop system, so please, take it for what it's worth, but the numbers sound right. Too much air cooling for the light can cause a shift in color spectrum. I would go for something along the lines of 100CFM-150CFM. I wouldn't think you would need more than 175CFM anyway.

Not a carbon-filter, but rather some kind of covering (like a 1/4" AC foam pre-filter or some such) for the intake for the light. Something to prevent bigger things like bugs and such from entering the loop. Try to make it easily removable for servicing/cleaning because it will get dirty and slow air flow to the light.

Pre-filtered intake>fan>light>exhaust. You want the fan pushing air through your light, rather than pulling. If there are any leaks in the system, you want it leaking into the grow area. As opposed to pulling any stinky air through those leaks bypassing your second stage carbon-filter.

Exhaust out of one window that is down-wind so that you don't draw exhausted hot air back into the intake for the light. Kinda defeats the purpose of an air-cooled light. Most places have a "prevailing" wind direction. They will shift from time to time, but most times it will flow from one direction.

 

[purpLEsmoke]

Thank you man, i understand you not doing a closed loop system but i appreciate your help.

Ill be going with a inline fan from 100-175 cfm depending on what i can find, my other concern is how will i calculate the loss through the ducting?

The AC foam pre-filter sounds good for filtering , do you mean something along the lines of this

I use small filters for my computer case to block dust from entering but they arent very very tiny, small particles still do enter.

If i am pushing air through and there's a bit of dust that enters the light do you think it will flow through or will the dust particles attach the the high heat of the light?

As opposed to smell, i think i might skip the carbon filter, so you rate that pushing the air though will do enuf of the job to get it out of the other end of the cab? No need for back draft shutter or any other ancillary of some sort ?

I am planning on sealing the whole window on the left and leaving holes just for the exhaust, then using the right window with a pre-filter to push in fresh air ?

Appreciate your help bro !

PEACE

 

[messn'n'gommin']

Ya, that will work. The main thing is to keep the big stuff out. Little stuff will mostly flow through and what doesn't can be cleaned at regular intervals, as well as the hood's glass. A pain to be sure, but it beats dumping hot air into and then drawing from, the room.

I do have one question, even though the light is ventilated, the cab is still going to get warm enough to need some ventilation and without a carbon filter for the cab itself, do you really want everybody and their brother knowing you grow? Because two to four weeks into flowering, it will stink!

 

[purpLEsmoke]

So then two extractors one for the hood and one for the cab will be good ?

Dude no doubt i wanna keep the plants in a good environment and i also want the temps to drop by about a few degrees during the dark cycles to keep tight formation of the plants.

Im really excited and keen to get it going dude i want to get a carbon filter but the air is going to be pushed into a vegetable garden, thats why i thought maybe for the 1st time i can get away with it, the other reason is cash, the fans are going to set me back 250$ and a proper carbon filter from the store is 220$. I researched alot concerning my hood & alot concerning the digital ballast. To source the ballast here in this country was my biggest mission & the hood i had to wait 2 Months.

I dont hate DIY, although in certain scenario's it just doesnt quite get there. Maybe for somebody like me i should of gone a cheaper route. With my cab, i am, building it out of wood and panda film.

I cant afford to buy the wrong equipment thats why its taken so much time for me & also due to my region.

I would gladly appreciate any further help as for now im still pretty lost.

 

[messn'n'gommin']

Just to throw a wrench into the works (lol...and after all this), would a single fan ventilation/filtration setup be better for your situation? Forgetting, for now, a separate fan to cool your light hood?

interior cab fan>light>exhaust>filter

It will probably require a bigger fan and it's not the most efficient way to go, but it will work. It'll eliminate the expense for an extra fan, and at a later date when finances get better, you can go with your original two stage plan.

As an aside, if you're not fully confident with DIYing a filter, it might be better to invest in an off-the-shelf filter. DIY won't save all that much money (I guestimate about 25% of o-t-s costs) and if done poorly, violates a big part of "Grow Club."

No tell.
No smell.
No sell.

 

[purpLEsmoke]

Dude either i go for one fan and a Carbon filter or i go for two fans and no carbon filter.

Problem is when i do get a carbon filter, is my inline fan going to be too slow to pull air properly ? Should i compensate for this by getting a fan that can run a carbon filter nicely on highest speed and exhaust air without a carbon filter on its lowest setting ?

If i get a fan now and a carbon filter yes its going to be strong to pull everything through but when i attach my other fan to the hoods vent am i not going to be sucking too much through this carbon filter ?

I think growing indoors is a bitch for me cause im not the type of guy to scrap things, well i cant because shits fucking expensive here.

Ive spent countless hours & money on this stuff and i feel like im half way, im going to have to spend more to get my inline fans.

Although to be honest id rather have a good setup than a worse setup with a carbon filter, people dont hang around the place im growing, there's no people for a radius of about 10 meters in that place blocked by walls and trees etc.

I really dont give a shit about a carbon filter for now & neither do i want to make one thats DIY that cant match a fan properly.

This might be my first time but i am going to try the best i can to get the most yields i can, i cant even afford to put wear and tear on my equipment for a grow thats not going to be worth it, i need to get the grow room as optimal as i can.

My life pretty much depends on this.
Weed is expensive here, people f you around & its a risk meeting up with different people all the time.

I havent had proper blaze in 2 weeks, i go to bed at 7 am with my eyes watering from research, i live in the main city of my country but im moving the grow far out of reach ,couple of hundred km away. Petrol costs a arm and a leg too. So if i could get my equip, bounce & start the grow it would be amazing.

I really dont mean to come accross as a begger for help, im just in a situation. The guy i know has been giving me decent weed for a while, he went from giving me bubba kush x lemon haze that fucked my socks up to some BULLSHIT that has seeds, has no smell ( not cured ) & guess what ? it doesnt make me high ! Also i paid 5 % less than i did for the lemon kush.

Would really appreciate the help guys.

Peace

 

[mowood3479]

id get the biggest fan/filter combo u can afford.. its far better to have to much ventilation than not enough... Id also set up with fillter>fan>lights>exhaust.. no need for 2 fans really..
its really not as complicated as it seems.. a 6" can fan (400ishcfm)and a filter should do you just fine

 

[purpLEsmoke]

Thanx mowood, look definately will be going with bigger just dont want to go too big that i extract my plants into dehydration.

I have definately considered the single fan option dude, i was just reading that if i want to top up the plants with co2 it wont work with the single fan option, cause when i put the co2 in and shut the fan off the room will most probably overheat, if i use two fans, i can switch off the cab fan & keep the hoods fan on to keep temperature more or less in place.

Although i could probably use the single fan option & when i put co2 i could just attach ducting from my hood to the outside of the cab?

Dunno man im stressing tits for nothing ey...

 

[messn'n'gommin']

I fully understand a lack of finances (believe me, I do!), but maybe for all concerned we should take a step back and re-evaluate your options. I don't mean to step on any toes, but the harsh reality is, to grow your own, it's going to take a chunk of money (about the amount of an oz. or two of good weed) to start out with! In the long run, it will pay for itself, but, if it's a choice between buying and growing, I say give up buying, at least for a couple of months. The money saved will get you on the road to smoking your own.

Some principles are the same, from a huge warehouse grow to a pc grow. Namely, adequate lighting, ventilation, air-filtration, and a light-proof grow area. Taking care at the beginning can mean the difference between a bountiful and potent harvest or frustration and regret, especially for a first grow. Although, I encourage you to take heart, it is more likely somewhere in between. And above all, it will take patience! So, having said that, I would ask:

What equipment do you have on hand or have already paid for?

How much weed will you need per month?

As far as providing a decent grow environment is concerned, how flexible are you with what you want to do as opposed to what you can do?

 

[purpLEsmoke]

Thank you again for your reply man, i definitely think re evaluating is a good step.

If it means i should detox for a few months ill do it, knowing the rewards.

I plan on spending alot of time on these babies as i will have the time.

Your questions :

What equipment do you have on hand or have already paid for?
I have the 600 watt digital ballast from Accendo, 600w Sylvania Grolux, Super Sun 2 hood, 2 metre by 16 metre Panda Film, Mother & clone box is already made i will upload pics of it. Seeds: Greenhouseseeds The Church, Unknown: Eastern Star, Unknown : Jack Flash.
I have already researched and located the businesses to buy my other products eg. Hygrometer, Inline fans, Nutes ( Bio Grow ) , Organic promix , Clone box, reverse osmosis sytem etc.

How much weed will you need per month?
I am looking at acquiring 15 Oz per harvest

As far as providing a decent grow environment is concerned, how flexible are you with what you want to do as opposed to what you can do?

Im pretty flexible with what i want to do, im growing in a room thats 6.5 feet wide and 10 feet wide approximately.

Much respect for the help man.

 

[intotheunknown]

another thing to consider, and ALMOST makes it easier than calculating everything is to half ass calculate in the right size, in the right area... overkill the blower, get yourself a fan speed controller and make it all adjustable.

i find it difficult to calculate it all, get what you need, and struggle to dial in the room with a one speed fan on high constantly...

as ambient temps change, which is a lot, your room temps change too. so if youre able to adjust the air flow, you can make it FAR easier "dial" in your room. and most importantly keep it dialed.

now keep in mind that you also can go too big. some slight calculation will be required, just as long as youre in the range and youve got a speed controller. you should be good to go.

 

[purpLEsmoke]

Probably does make it much easier dude, so then if im using 1 blower on my cab and one on my light, i should get a blower for my cab that will be approximately matched on its lowest setting for the amount of cubic feet i want to extract ?

I know where you coming from though, it makes sense, its not easy to calculate because there's alot of variables.

Thanks for the tip, ill definately keep the calculation in mind, i also want to find out approximately how to calculate loss through the ducting. Too much air flow and ill be dehydrating the babies, not something i want to be doing.

Peace !

 

[intotheunknown]

honestly in a cab, i dont see the need for 2 blowers.
what i would do is make a passive intake at the bottom of the cab... (in my lung room i use light proof louvers found at camera and photography shops for intakes. rather expensive but well worth it.

pull the air from inside the cab through the passive(s) >through the hood to cool> and out to a scrubber... or your scrubber could be on the front. either way.

so essentially youre pulling a vacuum inside the room (negative pressure) also if scrubbing, no stink gets out unless there is a leak in your ducting.

now depending on your ambient temps, and your location. you should be fine with a single blower in that space size.

humidity i wouldnt worry so much about. get your temps dialed in first and humidity is something youll have to adjust as you get your grow going. will either have to add or subtract as far as that goes... maybe not. get some plants in there after your temps are in check and adjust humidity from there. plants in the room are another variable as far as humidity goes.

 

[JimmyRow]

I say 6" fan filter combo. And a speed controller. Also think about the noise. But it will mos def stink.

 

[messn'n'gommin']

filter>fan>light>exhaust

One filter. One fan. One light. Done.

This is a good rough guide to go by.

Get a fan just a bit higher than what the guide calls for. That will take care of what resistance the filter and vent tube takes out of it.

Now, get to growing!