too much negative pressure?
- Thread starter borbor
- Start date
RM3
Well-Known Member
NanoGadget
Well-Known Member
I read the linked article. Obviously the science is sound but there is no way an inline fan and a grow tent are ever going to produce pressures that low. Not going to happen. I'd like to see some numbers on what the falloff is on the effect and at what point it's impact on plant growth becomes negligible.
RM3
Well-Known Member
Well research is your friend, lots of info if one looks for it. Folks are always askin how I get the results I get with nothing but T5's 2 feet above the canopy and my answer is always, I understand lights and I understand barometric pressure (pics of my results in my sig)
nomofatum
Well-Known Member
I guess you would have to measure the pressure in there to know, but we clearly aren't going to get to 1/16 of earth, lol. So what do you target for pressures at different phases? Do you adjust for night and day? How are you maintaining a given pressure? Sounds like a bitch that would only really be possible if you go CO2 and all?
How did you determine ideal pressures?
How did you determine ideal pressures?
RM3
Well-Known Member
Didn't determine anything, my garden is wide open, my plants have access to natural barometric pressure
borbor
Well-Known Member
wow, cool I'm gonna look into vertical growing, I always thought that was the kind of thing you'd wanna do in like a whole room kind of setup, stadium idea looks cool though.OK a 3x3 space will fit your 4 plants, but, IMO, you will have only a couple weeks to veg them, not 6 weeks. Maybe veg for two weeks then flip, or you could leave the tent on 12/12 and put a seedling in every 2.5 weeks or so... The 12/12 thread has some nice looking plants!
You won't need a 2nd light in there with the sunsystems 315w lec , also don't get that light too close , @GroErr has the same light going. You should look up his thread called GroErr Grows...
Your mom is cool for letting you grow but electricity up front? Wtf? You should just calculate your monthly operating cost and pay that each month when the bill comes in, then split the difference between you and her.
You need to figure out how to either move air in or out that window without it being obvious from outside. In doing so you will probably put in curtains, so theoretically the tent COULD be in front of the window thus eliminating some spider webby ductwork. BONUS: if the tent is in the room and not the closet its easier to access and could be bigger! Like a foot or two or three bigger.
If you're looking to buy gorilla tent I've got a pretty sweet hookup, pm for details. I think he ships free to the attached 48.
Personally I think you could go with a can 33. I have a can50 for my 4x8 tent... My plants aren't super stinky yet but I expect the filter will do fine.
Also, vertical growing is something you may be interested in. I went vertical and I feel it's a good use of light and space.
View attachment 3323239
Ya I know it derails a thread but you may as well consolidate all your convo's and thoughts in one thread rather than have them spread out. I saw you posted another similar thread and that thread has pics that this one doesn't...
funny you should mention those things, I have a buddy who does 12/12 from seed with a 600 watt hps, I'm not a big fan, I'd like at least a bit of veg to train them, establish a root system before transplanting to a larger pot, and so on.
been all over groerr's threads, he makes me so happy I bought the lec 315, but also so upset I didn't google dna lighting for that 860 watt cmh. About getting another light, I know I don't NEED it by any means. One thing I've always been a pretty strong believer in is giving the plant a diverse spectrum, really interested to maybe do some grows with the 315 as the main light and compare the effects of an additional one or two high watt cfls, an led around 100 watts, and either a 150 or 250 watt mh and/or hps next to it. all in time. of course with the big IF I can figure out a way to get the air in or out the window, I'm assuming the overkill I put into my ventilation should be able accommodate overkill in the lighting. am I wrong there?
pretty sure I'm gonna go with a gorilla tent, I know in the long run that'll pay off, just salty about the dr90 I won't be using til I move again.
I don't even really think the problem with putting it in front of the window is related to visibility from the outside, just a nice looking house where everything is organized and stuff. I'll fly the curtain idea past her, I might be okay with a few feet of ducting near the window, gotta negotiate about that.
so 350 cfm wouldn't be too much for a can 33?
I've been considering those exhale co2 bag things, would that kind of thing help my situation at all? I would want to just get a tank and a regulator but I'm not even gonna float that by my mom. She's freaked out over dabs, she is not gonna want a tank of lethal colorless odorless gas in the house.
This is one of the big things I've always been confused about with passive intake.
How do you create a light proof passive intake?
always wondered about the true utility of those screens on the bottom most grow tents, mine has one on each side and the covers just velcro off. I see that they'd be useful for passive intake, but they're not lightproof, so how do you put those to use?
nomofatum
Well-Known Member
Vert is all about side lighting and floating lights. You want a smaller top light and something like T5HO or a grid of low power LEDs lining the walls. Vert uses a lot of low power lights so every part of the plant is in ideal weed producing light levels. Very cool, I will some day do a vert.
ayr0n
Well-Known Member
Hey man, I'm kinda in a similar situation. Not my mom, but my fiance was raised to absolutely hate marijuana, so I have to 'hide' my hobby. She knows about it, but part of our agreement was that she didn't smell, hear or see anything. If you're worried about the noise, you can find some consolation in the fact that even though the fans themselves can be loud as fuck, once you attach a carbon filter, a good deal of it will be muffled. Can't hardly hear my fan standing next to the tent, and when it was hooked up without the carbon filter you could damn near hear that shit outside the house. Sounded like a jet plane taking off in the basement prior to the filter, can't hear anything with it attached. It's a huge carbon filter, so that probably plays a role, but the noise reduction is significant.
This is how i had my first tent set up, not sure if that qualifies as 'roboctopus' but it was fairly simple n kept things quiet. Couldn't have guests coming over asking what that loud ass jet engine is in the basement, n this did the trick:
It's not the perfect layout n I'm sure plenty of ppl here can give you a better way to do ventilation but it's worked 4 me...my fan is wayyy overkill for that tent (my new tent is ~6x the size and it's still overkill for that), but with a fan speed controller you can dial it in to keep things where you need em. I was battling heat w/ a 600w in that tiny tent so I had to use an excessive amount of air exchange to keep things cool enough inside the tent without AC.
I've heard pushing the air out is better than pulling it like the way I have it setup (and heard vice versa
) but i couldn't figure out a way to mount all of that shit inside the tent and have room for the light and plants, so this is what I ended up with lmao.Good luck, hope u find a solution that accommodates both you and the home owner. Compromising can be a bitch, but it's better than nothing.
borbor
Well-Known Member
haha yeah ayr0n pretty similar situation, and similar overkill as well. That layout would totally work for me, but where are you pulling air from? gonna start flipping through your thread now.
some time a few months ago, I think on riu but it could have been somewhere else, I read about somebody getting another prefilter and putting it inside the can, presumably for the purpose of pushing air through instead of pulling, so I bought another prefilter, got it to the right size with paperclips and put it in the filter before I put the flange on. Anybody have any thoughts on whether that might alleviate some of the issue with pushing instead of pulling?
some time a few months ago, I think on riu but it could have been somewhere else, I read about somebody getting another prefilter and putting it inside the can, presumably for the purpose of pushing air through instead of pulling, so I bought another prefilter, got it to the right size with paperclips and put it in the filter before I put the flange on. Anybody have any thoughts on whether that might alleviate some of the issue with pushing instead of pulling?
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nomofatum
Well-Known Member
I would think a vent clamp and a flat filter should cut it, just put it over the fan intake and clamp down so it can't get sucked in ,trim if desired.
borbor
Well-Known Member
I've got a couple "bug screen" things that go over the end of ducting, would that be enough?
like this, but without a carbon insert
https://www.hydroponics.net/i/137076
like this, but without a carbon insert
https://www.hydroponics.net/i/137076
nomofatum
Well-Known Member
If this claim is true, I would say yes:
Active carbon inserts proven to catch all bugs, mold and mildew.
Mold spores are pretty small so if it can filter those I would have no concerns.
nomofatum
Well-Known Member
no a screen won't do, make a filter insert for it. Just find one you can cut at the store.
I mean you can run completely without it, but you will burn up the carbon filter by plugging it with dust. You really just need a dust filter.
Nizza
Well-Known Member
you make a light proof passive intake by first taking the area of your exhaust lets say it's 6"..
Now you take 3.14 (3")^2=28.27
multiply this by 3 = 84.81
a 10 " diameter circle will give us 78.54" or a 11 will give us 95.03.
this is an example of how to calculate the proper sized passive intake.
as for lightproofing , the rule of thumb is material should be black and non reflective inside, and the intake should make two 90 degree turns before being near light.
what i did was i took a rectangular box, 10 X 16 (160 sq ft), about 1 1/2 feet long, and cut in two diffusers. The diffusers have fins that will help trap the light ( paint black) and you also put filters in that help block off even more. remember you want two 90 degree bends in order to trap light. The reason i go way over the 3x rule is because i expect at least 50% restriction due to the filters and diffusers. Simple pipes doing two 90 degree bends would have much better velocity and barely any restriction.
you can also just do 3 seperate holes for the passive intake and use the same size as the intake , or the 1 big hole. My rule is always put the intake on the bottom, and the exhaust inlet diagonally across from it.
also you want 3x the diameter of the size pipe you use length wise from each side of a fan (6" fan would be 18 " before making a turn) before making any bends, if possible. two 45 degree bends are always better than 90 degree bends and always avoid making the air do a 180 degree bend, you want to always have the flow go in as straight of a path as possible.
the most ideal position in theory for a fan would be on the exhaust side , pointing up vertically (heat would help with flow), following the rule of 18" before making the two 90 or four 45 degree bends for the light trap. You also want the carbon filter the 18 " away from the fan. Usually the fan will horizontal end up in the grow then one bend will end up outside the tent and the other inside. This also muffles the fan because it is now in the room, but also restrics some space.
Now you take 3.14 (3")^2=28.27
multiply this by 3 = 84.81
a 10 " diameter circle will give us 78.54" or a 11 will give us 95.03.
this is an example of how to calculate the proper sized passive intake.
as for lightproofing , the rule of thumb is material should be black and non reflective inside, and the intake should make two 90 degree turns before being near light.
what i did was i took a rectangular box, 10 X 16 (160 sq ft), about 1 1/2 feet long, and cut in two diffusers. The diffusers have fins that will help trap the light ( paint black) and you also put filters in that help block off even more. remember you want two 90 degree bends in order to trap light. The reason i go way over the 3x rule is because i expect at least 50% restriction due to the filters and diffusers. Simple pipes doing two 90 degree bends would have much better velocity and barely any restriction.
you can also just do 3 seperate holes for the passive intake and use the same size as the intake , or the 1 big hole. My rule is always put the intake on the bottom, and the exhaust inlet diagonally across from it.
also you want 3x the diameter of the size pipe you use length wise from each side of a fan (6" fan would be 18 " before making a turn) before making any bends, if possible. two 45 degree bends are always better than 90 degree bends and always avoid making the air do a 180 degree bend, you want to always have the flow go in as straight of a path as possible.
the most ideal position in theory for a fan would be on the exhaust side , pointing up vertically (heat would help with flow), following the rule of 18" before making the two 90 or four 45 degree bends for the light trap. You also want the carbon filter the 18 " away from the fan. Usually the fan will horizontal end up in the grow then one bend will end up outside the tent and the other inside. This also muffles the fan because it is now in the room, but also restrics some space.
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