600 Watt Cool Tube/ 2'x3'x5' Tent/ Kush & Cheese - GreenhouseSeeds

[Midwest Weedist]

I'm still curious about how harsh winter temps would affect a bulb if vented directly to a cool tube hood.

 

[skunkd0c]

I'm still curious about how harsh winter temps would affect a bulb if vented directly to a cool tube hood.

it will not crack/break the bulb, you should be able to find vids or pics of folk who have connected Their AC unit directly to their cool tube/ducting
if it were cold water yes it would break the glass
just like when a glass cracks when doing the washing up

i would guess air can't conduct or remove enough heat quick enough or lower temp quick enough to cause the shock necessary to break the glass
i'm sure someone here will know exactly why, or just google it

peace

 

[MD914]

i think that trying to cool the air down after it has been heated by the lights in the space is not as effective
once the air space is warm/hot it takes a very powerful fan to extract all this air quick enough to lower temperature quick enough

imo it would be more effective to concentrate your efforts on directly cooling the lights before they get a chance to heat the air space too much
you could connect some ducting to your AC then connect it to your lighting system blow the very cold AC air across/through the lights

nothing wrong with putting the filter at the front on the same line as the cool tubes
the main disadvantage is you tend to put the filter up high so it will remove smell and humidity also
and the heat of the room, but its also this warm air that you will be sucking across the lights
which will not cool them as well,
its best to have the coldest air possible blowing or sucking through the lights
the filter will reduce it a little but not too much

i have run 4x600w lights with a smaller fan than yours, but not in a tent

your fan is powerful enough for 3x 600w lights under normal room temps
and powerful enough to bring in fresh air and do all the jobs by itself in an open room during the colder times of the year
during summer when outside air is much warmer, or in a tent i would look at bringing in some fresh air from outside
or your AC to help cool things down

i do not think AC is that great for the space the plants grow in, as they only recycle air
they do not bring in new co2 rich air
and they cost a fair bit of electricity to run

peace

I'm actually moving out of my enclosed spaces and into a 10 X 13 room

The purpose of the ac would be for the lights I'm just not sure how to tie it all together on the same run (instead of running 2 fans )

Thanks for your input...I'm so used to working in small spaces that I find myself stuck there and get a little confused

 

[ButchyBoy]

My fans do just fine pulling...your filter may slow it down though. Why aren't you running two fans as the diagram above shows? That's how I have both my spaces (and how my new ROOM is being set up) that warm air isn't going to melt your fan...my ducting doesn't even feel warm...and I can put my hand on my cooltube while light is on...

At the old house I had it set up separate. I had a 240cfm pulling fresh air in and through the lights then back out and my 440cfm pulling through the carbon filter then out. Here I have the 440 pulling through the filter and blowing through the lights then out.

With the 240 going through the lights, I could not get within 2 inches of the lights without feeling the heat. Maybe I need a larger fan for the lights so I can continue to use the 440 for the filter and passive intake.

most likely the fan will handle the heat although as they work constantly this will maybe cause them
to not last as long , most inline fans the cheaper ones the hydro shops sell are plastic blades
i have a boxed fan this uses metal blades, maybe the mental ones have a disadvantage too
if they are not fully rust resistant humid air could damage them

the main advantage of pushing air through the lights with the two fan system is not having to buy another carbon filter which cost as much as the fan itself
not having hot air directly in contact with the fan is a bonus but not essential

these fans are designed to work in hot factories, the direct heat they extract from the light is hotter than this
but not so much it will damage the fan instantly , i think it would take time to show damage due to excessive heat
you could look at the spec of your fan and see what its safe operating temps are

peace

I would hate to destroy this fan as I have read somewhere about one melting. I think today will be a test day. I will push the air through the lights with the 240 and see what the temps do. Time to go cut two more holes in the ceiling!!!

 

[skunkd0c]

I'm actually moving out of my enclosed spaces and into a 10 X 13 room

The purpose of the ac would be for the lights I'm just not sure how to tie it all together on the same run (instead of running 2 fans )

Thanks for your input...I'm so used to working in small spaces that I find myself stuck there and get a little confused

when you have your open space going, your will find things easier i reckon

most folk run it with one fan ( air direction << FAN> cooltube>ducting>cooltube >ducting>cooltube>ducting> filter < air direction )

because you are now going to grow in an open space instead of a closed tent or whatever
i do not think you will have any issues with temps at this time of year with 3 or 4x 600w
the air from outside that comes into the grow space is colder this time of year and helps to keep the room cool

during summer you might want to cool things down some more

10x13 room will be a nice big space and lots more air freely able to circulate around your plants

peace

 

[MD914]

At the old house I had it set up separate. I had a 240cfm pulling fresh air in and through the lights then back out and my 440cfm pulling through the carbon filter then out. Here I have the 440 pulling through the filter and blowing through the lights then out.

With the 240 going through the lights, I could not get within 2 inches of the lights without feeling the heat. Maybe I need a larger fan for the lights so I can continue to use the 440 for the filter and passive intake.




I would hate to destroy this fan as I have read somewhere about one melting. I think today will be a test day. I will push the air through the lights with the 240 and see what the temps do. Time to go cut two more holes in the ceiling!!!

Let us know your findings Butchyboy...or post them in your thread

I think it's a good conversation for here too though

 

[Midwest Weedist]

it will not crack/break the bulb, you should be able to find vids or pics of folk who have connected Their AC unit directly to their cool tube/ducting
if it were cold water yes it would break the glass
just like when a glass cracks when doing the washing up

i would guess air can't conduct or remove enough heat quick enough or lower temp quick enough to cause the shock necessary to break the glass
i'm sure someone here will know exactly why, or just google it

peace

Thanks, I'll definitely do some more digging on this. I know that in my area we get sub zero temps minus the windchill. I'd imagine that with a temperature difference of way over a hundred degrees you'd possibly break a bulb. Maybe not though. I'd expect that since a magnetic hps ballast heats up extremely fast (No slow start like a digital one) that it might pop if the bulb was sitting at freezing or below. Though I guess you could close off the ducting when the lights off? Idk, maybe I'll start another post and see what the folks say in the lighting threads.

 

[skunkd0c]

Thanks, I'll definitely do some more digging on this. I know that in my area we get sub zero temps minus the windchill. I'd imagine that with a temperature difference of way over a hundred degrees you'd possibly break a bulb. Maybe not though. I'd expect that since a magnetic hps ballast heats up extremely fast (No slow start like a digital one) that it might pop if the bulb was sitting at freezing or below. Though I guess you could close off the ducting when the lights off? Idk, maybe I'll start another post and see what the folks say in the lighting threads.

i think you are just being overly cautious , which is a good thing

this explains why it happens with water, i just do not think air is capable of causing this much temperature change
water conducts heat several times more efficiently than air


Like most substances, glass expands as it heats up and shrinks as it cools. It also has moderately low thermal conductivity. And it's hard but brittle. These three facts are why glass can crack when suddenly cooled. And ironically, the same principles allow us to make tempered glass extremely strong.

Imagine you have a hot, thick piece of glass. It's uniformly heated and thus is uniformly thermally-expanded. Now dunk it in an ice water bath -- the surface will cool almost instantly on contact, but the middle has to wait for heat to conduct away before it can cool. That creates an uneven thermal profile, where the surface is cold but the inside is hot.

As a result, the surface shrinks! Or it tries to. The hot inner glass prevents the surface glass from shrinking. This creates a powerful stress profile through the glass -- the surface is trying to shrink, but can't, so it is forced into tension. The hot core is trying to stay the same volume, but the surface is squeezing in, so the core undergoes compression.

Ok, so it's under stress now, so what? Glass has enormous compressive strength. And any confined solid subjected to purely hydrostatic stress (from all sides equally) is pretty much invincible. (You can drop an egg or a piece of fine china to the bottom of the ocean and the pressure will not break it.) Glass also has, rather surprisingly, enormous tensile strength -- in laboratory testing of ultra-pure specimens, tensile strengths over one million pounds per square inch have been observed. Under controlled conditions, glass is actually much stronger than metal.

But real conditions aren't controlled, and as we all know, glass is incredibly brittle. The tiniest flaw or scratch on the surface is able to act as a nucleation site for brittle failure. Once a fracture is initiated in stressed glass, cracks can spread and grow like a lightning bolt. Stress concentrates at the tip of the fracture, causing it to lengthen until the entire piece is cracked through. Sosurface glass under tension is very weak in practice. (Note that I say "surface" here. That's important later.)

So in our hot-glass-in-ice-water example, the surface is trying to shrink but can't, meaning it is suddenly under tension. And the core is put into compression by resisting the shrinkage. It's not hard to figure out which section of glass wins the tug-of-war -- the surface fails first. And a crack grows out of some microscopic scratch or flaw, growing and spreading until the stress is suffiently relieved or the glass is broken clean through.

That's why hot glass breaks when it's suddenly cooled. But there's a really cool way to use this effect to make glass stronger.

"Tempered glass" is glass that has been treated with heat to make it stronger and safer. A large pane of regular glass is heated to the point where it is soft and able to yield, so it is able to very slightly flow and redistribute internal stresses. Then the surface is blasted with cold air, causing it to cool and rapidly shrink just like the earlier example. But this time, the core is so hot that it is able to harmlessly yield a little, preventing a build-up of tension in the cooler surface layer. It's kind of like how a paper clip can be bent in half without snapping. Hot glass has some ductility -- it's not brittle.

So now the pane of glass has this cool, shrunken surface layer, and a hot, expanded core, and minimal stresses (unlike the earlier case). Now the entire pane is allowed to cool a bit slower, so the core is able to re-harden and shrink. As the core cools, it tries to shrink, but now the surface glass won't let it contract. So the core develops a large amount of tensile stress, because it wants to shrink, while the surface develops compressive stress as it's pulled by the cooling core.

Remember, glass is exceptionally strong in compression. And the inner core can't be scratched by daily use, so fractures aren't initiated and the high "laboratory" tensile strength of glass is able to come into play. So tempered glass gets the best of glass's material properties, without the downsides.

In order for tempered glass to crack, the surface must be put in tension so a fracture can propagate away from a surface scratch. But it's already in compression -- meaning breaking tempered glass requires overcoming all that residual internal compressive stress. Thus, the failure point is dramatically raised.

http://chicagowindowexpert.com/2...

And in an extremely fortuitous turn of events, as soon as a crack does manage to penetrate the surface to reach the high-tension core, the entire pane of glass shatters into tiny pieces. All that trapped internal tension just needs a single fracture to get it started, and the whole high-stress zone breaks itself to bits. This means broken tempered glass makes thousands of small pieces rather than large jagged shards. This is a huge safety feature in applications like cars where broken glass may strike passengers in an accident.

I find this to be a marvelous concept. By putting glass under great internal stress, we make it more resistant to external stress! Rapid cooling destroys regular hot glass, but strengthens really hot glass. Nifty stuff.

peace

 

[Midwest Weedist]

i think you are just being overly cautious , which is a good thing

this explains why it happens with water, i just do not think air is capable of causing this much temperature change
water conducts heat several times more efficiently than air


Like most substances, glass expands as it heats up and shrinks as it cools. It also has moderately low thermal conductivity. And it's hard but brittle. These three facts are why glass can crack when suddenly cooled. And ironically, the same principles allow us to make tempered glass extremely strong.

Imagine you have a hot, thick piece of glass. It's uniformly heated and thus is uniformly thermally-expanded. Now dunk it in an ice water bath -- the surface will cool almost instantly on contact, but the middle has to wait for heat to conduct away before it can cool. That creates an uneven thermal profile, where the surface is cold but the inside is hot.

As a result, the surface shrinks! Or it tries to. The hot inner glass prevents the surface glass from shrinking. This creates a powerful stress profile through the glass -- the surface is trying to shrink, but can't, so it is forced into tension. The hot core is trying to stay the same volume, but the surface is squeezing in, so the core undergoes compression.

Ok, so it's under stress now, so what? Glass has enormous compressive strength. And any confined solid subjected to purely hydrostatic stress (from all sides equally) is pretty much invincible. (You can drop an egg or a piece of fine china to the bottom of the ocean and the pressure will not break it.) Glass also has, rather surprisingly, enormous tensile strength -- in laboratory testing of ultra-pure specimens, tensile strengths over one million pounds per square inch have been observed. Under controlled conditions, glass is actually much stronger than metal.

But real conditions aren't controlled, and as we all know, glass is incredibly brittle. The tiniest flaw or scratch on the surface is able to act as a nucleation site for brittle failure. Once a fracture is initiated in stressed glass, cracks can spread and grow like a lightning bolt. Stress concentrates at the tip of the fracture, causing it to lengthen until the entire piece is cracked through. Sosurface glass under tension is very weak in practice. (Note that I say "surface" here. That's important later.)

So in our hot-glass-in-ice-water example, the surface is trying to shrink but can't, meaning it is suddenly under tension. And the core is put into compression by resisting the shrinkage. It's not hard to figure out which section of glass wins the tug-of-war -- the surface fails first. And a crack grows out of some microscopic scratch or flaw, growing and spreading until the stress is suffiently relieved or the glass is broken clean through.

That's why hot glass breaks when it's suddenly cooled. But there's a really cool way to use this effect to make glass stronger.

"Tempered glass" is glass that has been treated with heat to make it stronger and safer. A large pane of regular glass is heated to the point where it is soft and able to yield, so it is able to very slightly flow and redistribute internal stresses. Then the surface is blasted with cold air, causing it to cool and rapidly shrink just like the earlier example. But this time, the core is so hot that it is able to harmlessly yield a little, preventing a build-up of tension in the cooler surface layer. It's kind of like how a paper clip can be bent in half without snapping. Hot glass has some ductility -- it's not brittle.

So now the pane of glass has this cool, shrunken surface layer, and a hot, expanded core, and minimal stresses (unlike the earlier case). Now the entire pane is allowed to cool a bit slower, so the core is able to re-harden and shrink. As the core cools, it tries to shrink, but now the surface glass won't let it contract. So the core develops a large amount of tensile stress, because it wants to shrink, while the surface develops compressive stress as it's pulled by the cooling core.

Remember, glass is exceptionally strong in compression. And the inner core can't be scratched by daily use, so fractures aren't initiated and the high "laboratory" tensile strength of glass is able to come into play. So tempered glass gets the best of glass's material properties, without the downsides.

In order for tempered glass to crack, the surface must be put in tension so a fracture can propagate away from a surface scratch. But it's already in compression -- meaning breaking tempered glass requires overcoming all that residual internal compressive stress. Thus, the failure point is dramatically raised.

http://chicagowindowexpert.com/2...

And in an extremely fortuitous turn of events, as soon as a crack does manage to penetrate the surface to reach the high-tension core, the entire pane of glass shatters into tiny pieces. All that trapped internal tension just needs a single fracture to get it started, and the whole high-stress zone breaks itself to bits. This means broken tempered glass makes thousands of small pieces rather than large jagged shards. This is a huge safety feature in applications like cars where broken glass may strike passengers in an accident.

I find this to be a marvelous concept. By putting glass under great internal stress, we make it more resistant to external stress! Rapid cooling destroys regular hot glass, but strengthens really hot glass. Nifty stuff.

peace

That was extremely informative, thank you. I appreciate these kind of posts so much. This makes me a lot safer feeling about ducting fresh winter air to my bulbs.

 

[GibbsIt89]

extracting/sucking air (negative pressure) is more efficient than pushing air when it comes to removing air from the space
negative pressure also helps control humidity better

if you push/blow air, (positive pressure) the maximum amount of air pressure the space can hold will need to be reached before air leaks out or is removed from the space

it is less work for a fan to remove air directly from the space (suck the air out) this instantly causes a negative pressure
air will flow in the direction from outside the tent to inside the tent
the result is the air is replaced quicker this way

imagine you have a fish tank of water its 3/4 full , you can add more water and keep adding water to cause the tank to over flow
this will cause water to flood out, eventually all the water will be mixed in with the new water

or you could suck the 3/4 full tank of water straight out and replace it with new water continuously

when using a 2nd fan to directly cool the lights it is ok to use positive pressure and it has advantages
but this is only when you are using 2 fans overall
one to cool the lights
one to provide air changes (co2) and control humidity

if you blow/push with the second fan

1 you do not need a 2nd carbon filter , the air through the lights will not come into contact with the air in the grow space because the positive pressure in the cool tube and ducting
keeps the air from the grow space entering the cool tube so no filter is needed less resistance less cost

2 the air space inside the ducting is small so the positive pressure can build up almost instantly

3 you can take air (cold) from outside and this will cool the lights more than sucking warm air through them from the grow space, some folk with lots of lights use an air conditioner to blow cold air through the lights instead of a fan blowing

4 the hot air does not come directly in contact with the fan

when people only use 1 fan, extracting makes more sense because the 1 fan is doing all jobs
cooling the lights, bringing in new co2, controlling humidity
using 2 fans separates the jobs between the fans

if you only had 1 fan pushing air through the lights
it would cool the lights quite well but it would not bring in new air very well or control humidity very well compared to extracting


peace

I was going with your diagram design already. Thats wicked though thank you!

Thank you for explaining.. although I already knew and agree with all of this you have said. What I think I am confused about is that "filter to fan to cooltube, as one straight line exhausting out of the tent" to me is still creating a negative pressure in the tent, if im sucking air out at a faster rate then what is coming in then that is creating a negative pressure. My fan/filter is NOT blowing around in my tent not attached to anything with the top open if thats what you mean.. then i can see what your saying where my tent is just filling up with fresh air then venting itself out at the top. My fan is directly sitting on top of my filter sucking air out of my filter through the ducting connected to the cooltube out the side of my tent. Everything is sealed up, this should be creating negative pressure. If I did filter connected to the cooltube and had the fan at the end of the cooltube sucking air through all of that exhausting out my fan would be working harder, my filter will not have as great of suction and I will sucking hot air into my fan rather than pushing fresh air over the bulb.

My original question i guess is it better to push air through a cooltube or suck air through a cooltube. I think sucking air through the cooltube with the filter at the front is harder on your fan and doesnt create as much suction where if you had your filter and fan at the front of the cooltube

 

[Greenhouse;save]

Imo...in laymens terms ...and I think most folk will agree..summer when temps r soaring then 2 seperate fans(or an ac unit)r defo needed then as winter creeps in and temps become less say....friendly then yes you could get away with 1fan albeit a good fan BUT then u have to factor in the RH if your fan is strong enuff to create a balance wich is not very often then fine but if not u r back to the 2 fan scenario which in my honest op every room,tent,hut,or just a big old space should ALWAYS have 2 fans better control is always needed in an indoor inviroment ....

 

[GibbsIt89]

to do with my last post... the pictures, It works fine like this for my 400watt and temps stay fine.. for the 600watt not the case.. it would be dumb to keep it setup like this even with cold fresh air intake.. with two fans and the diagram I think we all agree yes... that the 2 fan is the most ideal.. Even if its not needed because temps are high, it allows you to get your light closer then still.

after reading all of your posts doc... i think you and everyone just assumed that i didnt have the other end of the cooltube exhausting out of my tent and that it was just blowing around lol

 

[skunkd0c]

I was going with your diagram design already. Thats wicked though thank you!

Thank you for explaining.. although I already knew and agree with all of this you have said. What I think I am confused about is that "filter to fan to cooltube, as one straight line exhausting out of the tent" to me is still creating a negative pressure in the tent, if im sucking air out at a faster rate then what is coming in then that is creating a negative pressure. My fan/filter is NOT blowing around in my tent not attached to anything with the top open if thats what you mean.. then i can see what your saying where my tent is just filling up with fresh air then venting itself out at the top. My fan is directly sitting on top of my filter sucking air out of my filter through the ducting connected to the cooltube out the side of my tent. Everything is sealed up, this should be creating negative pressure. If I did filter connected to the cooltube and had the fan at the end of the cooltube sucking air through all of that exhausting out my fan would be working harder, my filter will not have as great of suction and I will sucking hot air into my fan rather than pushing fresh air over the bulb.

My original question i guess is it better to push air through a cooltube or suck air through a cooltube. I think sucking air through the cooltube with the filter at the front is harder on your fan and doesnt create as much suction where if you had your filter and fan at the front of the cooltube

from your pics it looks like you are extracting air in at the bottom of the tent and blowing it out to the right of the picture
this is the same as the 1 fan system extracting accept you have your filter near the bottom of the tent instead of the top above the light


there are different advantages to both
although blowing air through the lights with a separate fan is better obviously
or you could use a separate fan to suck air, but then it will need a carbon filter
as it will suck all the smelly air through the light
but if you only want to use 1 fan then extracting is better, which is what you are doing now

 

[MD914]

to do with my last post... the pictures, It works fine like this for my 400watt and temps stay fine.. for the 600watt not the case.. it would be dumb to keep it setup like this even with cold fresh air intake.. with two fans and the diagram I think we all agree yes... that the 2 fan is the most ideal.. Even if its not needed because temps are high, it allows you to get your light closer then still.

after reading all of your posts doc... i think you and everyone just assumed that i didnt have the other end of the cooltube exhausting out of my tent and that it was just blowing around lol

NO!! We all are well aware that your venting...

We are trying to tell you that when using one fan it's more efficient to PULL air through cooltube rather than to PUSH. We are telling you this based on science and personal experience

I run 2 fans in both of my spaces...and I always PULL air rather then push it because it is more efficient (even when running seperate fan for filter)

I'm going to be quiet again

 

[skunkd0c]

NO!! We all are well aware that your venting...

We are trying to tell you that when using one fan it's more efficient to PULL air through cooltube rather than to PUSH. We are telling you this based on science and personal experience

I run 2 fans in both of my spaces...and I always PULL air rather then push it because it is more efficient (even when running seperate fan for filter)

I'm going to be quiet again

yep thats it in a nutshell ^^
pulling is always going to be more efficient
with the two fan system pushing is used mainly to save the cost of a 2nd carbon filter
and the peace of mind heat is not in direct contact with the fan motor or blades
pushing with an AC is the best way to push air through the lights as its very cold

2nd fan could be done away with on bigger grows if the 1st fan is very powerful but for most people its just practical to have a 10-12 inch fan
they are very noisy and bulky ducting

 

[MD914]

yep thats it in a nutshell ^^
pulling is always going to be more efficient
with the two fan system pushing is used mainly to save the cost of a 2nd carbon filter
and the peace of mind heat is not in direct contact with the fan motor or blades
pushing with an AC is the best way to push air through the lights as its very cold

2nd fan could be done away with on bigger grows if the 1st fan is very powerful but for most people its just practical to have a 10-12 inch fan
they are very noisy and bulky ducting

The air that is pulled through my cooltubes currently comes from outside of the growing space (in one side out the other) so no need for odor control

 

[GibbsIt89]

NO!! We all are well aware that your venting...

We are trying to tell you that when using one fan it's more efficient to PULL air through cooltube rather than to PUSH. We are telling you this based on science and personal experience

I run 2 fans in both of my spaces...and I always PULL air rather then push it because it is more efficient (even when running seperate fan for filter)

I'm going to be quiet again

LMAO fuck my life. Sorry guys.. I still see it being better to have the fan on the front end of the cooltube rather than the back end. You are causing your fan to work harder, the filter is not pulling as strong because your fan has to pull all of the air from the cooltube and ducting before it pulls from the filter instead of pulling from the filter first. Therefore with my thinking i feel it is pushing a tad bit of cooler air over the light. All in all it is still creating negative pressure and everything is fine but ya im really trying hard here to picture it making more sense with the fan at the end.. does that really create more suction? hmmmm haha sorry guys. AGAIN I will be going with the 2 fan setup as doc's diagram shows so no need to respond to me if your annoyed lol.

 

[GibbsIt89]

from your pics it looks like you are extracting air in at the bottom of the tent and blowing it out to the right of the picture
this is the same as the 1 fan system extracting accept you have your filter near the bottom of the tent instead of the top above the light


there are different advantages to both
although blowing air through the lights with a separate fan is better obviously
or you could use a separate fan to suck air, but then it will need a carbon filter
as it will suck all the smelly air through the light
but if you only want to use 1 fan then extracting is better, which is what you are doing now

Ya because of the small space its hard to get the filter up really high.. i could get it up another foot mayb but thats pretty much the way it would have all ran if i was sticking with the 400..

 

[Greenhouse;save]

yep took the word right out of my mouth ....this from a man who has a MASSIVE filter taking half his room up and has it sitting on the floor .....genius.....

 

[skunkd0c]

LMAO fuck my life. Sorry guys.. I still see it being better to have the fan on the front end of the cooltube rather than the back end. You are causing your fan to work harder, the filter is not pulling as strong because your fan has to pull all of the air from the cooltube and ducting before it pulls from the filter instead of pulling from the filter first. Therefore with my thinking i feel it is pushing a tad bit of cooler air over the light. All in all it is still creating negative pressure and everything is fine but ya im really trying hard here to picture it making more sense with the fan at the end.. does that really create more suction? hmmmm haha sorry guys. AGAIN I will be going with the 2 fan setup as doc's diagram shows so no need to respond to me if your annoyed lol.

your filter is supposed to be at the front end so the air spends the correct time inside the filter
so it is filtered correctly , if you put the filter at the end, all the smell is being pulled through the fan and ducting
before it hits the filter, normally people only do it this way so they can put the filter outside the tent to save space inside the tent