grow tent setup question

I have a 4x8x8 grow tent with a 1000 watt hps connected to a carbon filter and a 6" inline fan for exhaust. I also have a window AC unit blowing directly into the tent. The temp hovers right around 75 and the rh around 50. My question is how important its air intake into the tent?

I was considering a 4" inline fan for air intake, how necessary would that be?

And any other ideas for the setup would be appreciated

Thanks

Isn't the AC unit blowing fresh air from outside into the tent??? Does your fan sans the AC unit provide negative pressure in the tent...if so there should be passive intake if you open the lil' screened vents. Not sure if the pressure would be there if you are forcing air in with the AC unit. That might even negate the filter....if the filter isn't sucking all the air thru it before expelling it outside, scrubbed.

Yes the AC is pulling air from outside and blowing directly into the tent. I wasnt really sure if it is providing enough fresh air for the plants.
The filter does seem to be scrubbing the air. But I am a little unsure about the air pressure in the tent. How can that be measured and is negative pressure good or bad?

The AC does not run constantly, it is on an economy setting it runs about 15-20 mins every hour. It keeps the temp right where it needs to be, my concern is whether or not the plants are getting the fresh air they need. I will try to post pics of the setup so it can be better evaluated.

I have nothing blowing air into my tent. I rely on the fan to suck hard enough to pull fresh air thru the vents, passive air intake I believe it is called. I've done 1 grow so far and they seemed to get good air flow.

The way I first "measured" it was.....hehehe, by puffin' out side the tent vent/windows and exhalin' nice n' slow.....and I watched the smoke. It QUICKLY got sucked into the tent. Also, i can see the sides of my tent being sucked inwards from the negative pressure. So yes, negative pressure is a good thing....it ensures that no plant smells are leaking out the vents/windows.....by sucking so hard it constantly pulls fresh air into the tent.

**edit** - I think that with the ac blowing extra nice n' chill air into the tent, you've nothing to worry about.

Glad to hear it. Thanks for the input.

May have to try your technique just for fun lol.

You should be just fine with every thing you have explained. Your plants will be VERY happy with a nice little window shaker A/C close by. Good luck. STAY HIGH!!!

I don't think one 1000 watt hps is enough light for your 4x8 tent. I'm using two of those in the same size tent have you checked your light footprint?

window a/c units don't use outside air. if the return on the a/c unit is in the room then all it is doing is cooling the air in the room. the back of the units pulls in air but that is only to cool the coils. that air doesn't mix with the room air. you don't need an air intake but you should be scrubbing the air in the room with a carbon filter either way.

Tony Sativa said:

I don't think one 1000 watt hps is enough light for your 4x8 tent. I'm using two of those in the same size tent have you checked your light footprint?

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I thought that too...but I am rocking a 5x5 with 1k.

nuglets said:

window a/c units don't use outside air. if the return on the a/c unit is in the room then all it is doing is cooling the air in the room. the back of the units pulls in air but that is only to cool the coils. that air doesn't mix with the room air. you don't need an air intake but you should be scrubbing the air in the room with a carbon filter either way.

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Oh I see what you mean....I suppose I ASSumed he has the ac unit outside the tent blowing into...then the air intake on the ac woulda been from outside.

Ahhh it is a window unit he said

smc5w said:

I have a 4x8x8 grow tent with a 1000 watt hps connected to a carbon filter and a 6" inline fan for exhaust. I also have a window AC unit blowing directly into the tent.

Click to expand...

So it has to be pulling fresh outside air in then eh?

I am using a carbon filter in my exhaust, should I also be scrubbing the air while it is inside the tent?

Also, I am expecting to get my second 1000 watter within the next day or two.

Heres the best pic I have right now

Ahhhh ok so it is backed up to the window.

I think that AC might be sucking air out of your tent....thus putting the smelly outside your window. There is a filter on the front I'm sure....you'll notice how dirty it gets on the side facing the tent...because like I said I think it sucks air from in the room. That could be an issue if you are trying to keep smell down.

On the other hand, if you continue that way, I'd closes all the other vents/holes/intakes on the tent.....having that window side open will allow plenty of fresh air in....I just wonder if your filter and fan can create enough suck to not let anything escape the tent.

smc5w said:

I am using a carbon filter in my exhaust, should I also be scrubbing the air while it is inside the tent?

Also, I am expecting to get my second 1000 watter within the next day or two.

Click to expand...

i have the 8x8 tents and i'm switching from 2 8x8 tents to 3 4x8 tents and gonna run two flower tents on a flip. the one thing i can tell you is that you don't need 2 1000w lights in that tent. if you can cool them then that is totally fine. i just found that running 1000w lights in tents creates so many smaller issues you have to deal with. plike you can't grow as tall of plants and you have a lot of cooling issues. i'll be running my lumatek ballasts dimmed to 600w with 600w bulbs and stillget plenty of penetration and enough footprint running 1200w as opposed to 2000w in the tent.

if i were you i would put your lights on a closed loop. have them draw air from outside of the tent and exhaust it back outside. make sure to seal your hoods and then use you carbon filter with a fan to recirculate the air in your tent. you do not need and air intake especially since you have an a/c unit. your a/c unit might be leaking a small amount of odor outside. it really all depends on the design of it. the front grate of your unit is the return. the air to be cooled is pulled in through there and then passed over the coils and blown back out of the vents. they are not designed to use outside air or exhaust air back outside. a lot of them are completely sealed but some of them aren't. even then they probably do not exchange air outside because your fan is running the whole time even if your comdensor isn't. this keeps positive pressure in the cooling chamber of the a/c unit and doesn't allow air to escape out the back of the unit. a/c units are not designed to bring cool air from outside, chill it, and put it into your room. they are designed to take air from in the room; remove the heat from it and then put it back into the room. this is how the work efficiently. if they used outside air they would never be able to get ahead because they would always be cooling the air based on the temp outside.

also, use some duck tape to seal the tent opening that the a/c sits in. tape it to the wall.