Passive intake

Discussion in 'Grow Room Design/Setup' started by LoUdPacCBoii, Nov 25, 2014.

  1. If I have a passive intake. Will this drop humidity by 10% or so.? Seeing as constant airflow is now being circulating in and of the tent?
     
  2. You might have to go into some more detail to get answer


    Sent from my iPhone using Grasscity Forum
     
  3. I don't see why exactly a passive intake will change the situation in comparison with a active intake. You can always increase the humidity with a bowl of water and reduces the humidity with a dehumidifier.
     
  4. ok I'll figure it out i already dropped humidity which was my goal. Now iam 2 hotter then I want it to be due to installing a extra light
     
  5. OK...

    First advice...don't worry about humidity.

    Where does this stuff grow best wild? Tropics, from jungle to high desert. As in deserts have a month a year of "This is a fucking desert? yeah, right. if I could find a surfboard, I could make it to India from Afghanistan surfing the wadis" and the rest of the year spit evaporates before hitting the ground it's so dry out. And jungles matching Forrest Gump's commentary "There was little stinging rain, and big fat rain that fell off leaves, rain that blew in sideways, even rain that came from underneath"...takes 75%-80% humidity MINIMUM to create rain. And tropical jungle in the "dry" season is still so humid you can drink 2 gallons of ice cold water, spaced evenly during the day, while doing next to no work, and get heatstroke...sweat just won't evaporate fast enough to cool you, the air's so humid.

    WA state, and British Colombia, CAN have worldwide reputations for killer outdoor weed...outside of July and August (and late June), humidity is always 65%-80% MINIMUM. July and August, 10% is high.

    The plants can take the humidity...it's the fungal infections you have to watch for. Which are humidity related. Too dry, dry mold and some forms of mildew are likely. Too wet? bud rot, leaf rot, and plain old white mold. Get a pump sprayer and some GreenCure, spray every two days...on and under leaves. Solved.


    Temps and humidity...warmer air holds more vapor. You can have a liter of water suspended in a cubic meter of air at 20 degrees C, and it could read 90% RH...because 10% more water suspended in it, it absolutely CAN'T hold another iota. At 80 degrees, the RH might read 30%, because it could fit another 2 liters and change of liquid water worth of vapor before being unable to hold more.


    Heat issue...NEVER go active intake, IMO. Active intake means a fan pushing air in. Two issues with this.
    First, this means large volumes of air passing through small surfaces...even a 14" oscillating fan is producing fairly severe windstorm level winds in its cone. A SERIOUS fan is putting out tropical storm to hurricane winds where it gets fed in. How would the plants do in nature constantly exposed to such conditions? They don't do well if they face 'em for a couple DAYS, do they?
    Second...air moves from higher pressure to lower pressure. A fan works by compressing air heavily enough that the pressure differential moves that volume of air that fast. Compression heats, decompression cools. That's why when you use a spray duster on your computer, the can gets cold as hell, and the air tanks on a portable jobsite air compressor are always hot, compared to the surroundings.


    You don't describe how you're moving air over your heat sources/lights. It makes a difference. If you attach a duct to the INTAKE of your exhaust fan, and put the opening of that duct so as much of the airstream as possible passes over the bulb, it steals a LOT more heat, cooling the bulb better, extending its life, and removing more heat than if you blow OVER the bulb, even through a ducted hood.
    Remember what I just said about wind? It's air moving from higher pressure to lower pressure? And as it expands (becoming lower pressure), it gets colder? DRAWING air over your bulb keeps the heat from being pushed out into the tent via hood leaks, takes more heat directly off the bulb, so it doesn't get transferred to surrounding air.

    Additionally, passive intake means negative pressure situation. Lower pressure in the tent than outside, or the intake wouldn't happen at all. Higher pressure outside, lower pressure inside, means as the air enters, it expands. Cooling, in the process. If I remember right a difference of 1 g per sq meter in pressure means a change of 1 degree per cubic meter, Centigrade.
     
    I'm not sure of that formula, so look it up if you like, but the principle is there. Same amount of sunlight, same conditions, same day, same humidity, all else the same, it's cooler in Denver than on the Oregon beach at the same latitude.
     
  6. just have the passive intake setup . Thanks for the knowledge I definitely put it to good use. Lol
     
  7. Our outside humidity is 80% today. Passive intake with the house cooling system running keeps the tent at 45-60% max.
     
  8. Hygrometer is a good purchase to start with. No need to do anything expensive if you have no problem.
     
  9. I have one thanks got humidity down to 47% with a passive intake
     
  10. brother you are golden with that, especially in flowering. You could get away with much more in veg or even flowering. Just have to stay on top of it. People have to try really hard to have problems with this weed. LOL! Once you have absorbed all the guides here I can not see too many problems. As you know you will have them, just do not panic.
     
  11. thanks for the advice gc has helped me a lot thanks again!
     
  12. #12 greaterthings123, Nov 29, 2014
    Last edited by a moderator: Nov 29, 2014
    You are mis-leading people.  To not think about humidity when planning a grow is a recipe for loss n yield.  I have lived in WA all my life.  RH levels are nothing like you stated.  10% in July and August being high is BS.  60 to 80% minimum the rest of the year is BULLSHIT as well.  Google something before you make random assumptions to appear smart.
     
    The humidity in certain stages of certain strain grows is VERY important in inceasing yields and quality... of coarse a plant will grow in many extrmes, but youcan give it an environment that is perfect.  Which can mean the difference of 1 1/2 oz to 6 oz on a small plant.
     
    Don't worry about humidity.... pffft. Who is this guy?
     
    EDIT:  I just kept reading on with what this guy was advising and it pissed me off even more.  I cannot believe how many likes the post got.  Beware who you listen to.  Some note worthy blades to listen to on Grasscity would be Ironhead, Snoopdog6502, August West, Pokesmot, and more.  Of those I listed, all would be more than willing to help out a new setup.  Nobody with any sense or experience would give the advice this guy is giving.   
     
    Passive intake is good.  Active intake is better.  What level is your RH at that it is worrying you?  Are you in veg or flower?   
     
  13. ok then... what is a good humidity then ? I have it 40 50%?
     
  14. Are your plants in veg or flower?  40-50% is a great place to be in both stages.  If I could keep mine there the whole grow, I would.  What you should do is develop a plan to deal with both extremes.  What will I do when humidity is too high?  Too low?  Humidity is more of a risk if flowering when it is higher than 60%.  Among other things, High humidity causes bud mold and will ruin your whole cycle.  Hooking an intake fan to a timer to go on and off accordingly to what you are trying to keep RH at is a great way to solve high humidity issues.  Also, you want a fan inside your room circulating air within.  Ideally, you want leaves fluttering and stalks ever so slightly weaving.   In extreme circumstances, a dehumidifier solves high RH problems in most small level grows. 
     
    Low humidity is less of an overall problem, but preventing humidity from getting too low can reduce stretching and airy bud growth.  Keeping it in perfect ranges will allow the plant to grow at its maximum potential all the time.  I find that frozen jugs of ice water suspended from the ceiling help me with low RH when I find it necessary.
     
    A more permanent option would be a humidifier outside the grow room but near your passive intake. 
     
    Enlighten us with more info.  What is your setup like?  closet?  room?  what lights?  what are you planted in? what are you feeding?
     
  15. just a 4x4 with mars 2 light 900 w . Fox farm nutes switching to organics here next go. It's a tent . Planted in 5 gallon pots strain kosher tangie
     
  16. Have you started a journal yet?  I'd like to see that Mars LED in action.  Is that 900 watts actual draw?  What kind of soil?  Organics is something I want to try out too... eventually.  Are you going to use live soils and teas... or organics to what level?  August West and Clackamas Coot are 2 very knowlegable organic growers.   
     
    I'm not ready to make the switch yet thogh.  I am messing around with coco and other soiless mediums currently.  I'll try dwc hydro soon.  Then I'll finish by learning organics.  Sorry so long winded...  
     
  17. #17 Indie-Kah, Nov 29, 2014
    Last edited by a moderator: Nov 29, 2014
    http://weatherspark.com/averages/29777/Bellingham-Washington-United-States

    RH highs typically over 90% as an average, uniformly (that's when it rains) for here (one of the highest humidity areas in the state).

    Listed lows are for Bellingham, right on the waterfront. and August is our driest month. Humidities as low as 10% are "normal" (as an average humidity, no). Average, you were correct for this side of the hills. I went and used the span across the state. 
     
    http://weatherspark.com/averages/30356/Spokane-Washington-United-States

    Dry side: Spokane, still great reputation for growth, AVERAGE low humidity between 26% and 14% over a 20 year span, not unusual the past several years (which have been rather dry) to drop below 10% multiple straight days. The chart claims 10% of the time, you get RH below 15%-20% in that period...again, that's a 20 year average. We've had the driest summers in documented history the last 3 years.

    I exaggerated a hair at "10% is high", yes. The point was what it remains...it is "unhealthily low" by "by the book" folks, yet the plants grow like mad, and produce quality known worldwide.


    EXACT center of average, over 20 years, is 45% at July/August (this span includes 5 record-breakingly wet summers), and 78 and 85 respectively at outdoor planting and cropping in Bellingham. Take a look at that same chart, you'll notice the high side bands are more narrow? That means it spends more time in each of those ranges. The lighter colored bands above and below each representing 25% of the time, the darker bands 10%, on averages...so 1 in 4 years, average is NORMALLY over 90% at plant and crop, 1 in 4, it's UNDER 23% on the dry side at lowest.

    Both being ranges you're trying to claim are unsustainable or damaging...yet yield from both areas prove differently.


    But you are right, we agree on one thing...indoor growers are supposed to be doing their best to give them "ideal outdoor conditions". Where we're differing is what we consider "ideal conditions".
     
    With the ranges of conditions (humidity and temp wise) the plants do well in, in nature, both indicas and sativas, I do, and will continue to, take the stance that so long as it stays within "normal tolerances" for places it grows well and easily outdoors, or naturally and without any human effort at all outdoors, as long as you don't SUSTAIN the maximum and minimums, but keep it within those ranges, the plant's going to do fine.

    Light energy, I take a different stance on, since we can't even match fall sunlight in Anchorage light intensities, usually, much less those in Ecuador, the only way to deliver the same amount of light energy is over a longer period. Ecuador, you ALWAYS have about a 12/12 sunlight pattern, slightly more blue during veg, slightly more red during planting and cropping...but much more direct and enough more intense to be noticible, at 45 degrees, summer gives you pretty close to an 18/6, equinox (March 21 and Sept 21, I believe...somewhere between the 20th and 23 of each of those, for certain) gives you 12/12, with a heavier balance of red.

    Since making light match these patterns and intensities is more than a bit problematic, I endorse doing your best to provide a consistent average in light conditions. It works. For verifiable reasons.


    As I've said many times, the "by the book" answers are averages for those trying to sustain a "perfect" condition...nature doesn't give consistency, it gives a range. The plants evolved over millions of years to natural conditions. Even line breeding and deliberate in-breeding of domestic stock takes nearly 80 generations to truly fix a trait difference enough to make a "different breed"...outdoors, that's usually one generation a year. Indoors, depends on cycles used, obviously. We haven't been earnestly tinkering with strains for anywhere near 80 years. All we've done is, figuratively speaking, had a pattern of breeding chihuahuas to pugs, then breeding their children together, to fix traits that are NOT sufficient to create new "breeds", just hybrids with traits of both that are not yet separate enough to be a new "breed".

    And yes, you'll find some cases where the results have been touchy as hell...just like if you breed a boxer to a rottweiler, your pups have a higher chance compared to most dogs of BOTH cancer and displaysia. You won't have a new breed, you'll have a crossbreed subject to the inbred weaknesses of BOTH. In which case, their tolerance for the ranges may be more restricted...or they may simply be more subject to diseases of certain types than normal.

    But since plants uptake their water via their roots, and we artificially water the plants...air humidity has dick-all to do with how much water they get for their use, and ONLY with what types of fungal infections they may or may not be subject to. Water a lawn in Phoenix (or even the Mojave) a couple times a day, despite the fact it's usually in the 6%-16% range over summer, you'll have as nice a lawn as you do in Seattle without a drop of watering. Or a hydrangea, or grape vines, blueberry bushes, or cherry trees, or barley...assuming the sustained temps aren't outside those plants' "survivability" range at any given period of sufficient length.

    Palms are touchy as hell, for instance...if they have extended periods of below 40 weather, they'll usually croak...but they do fine with no care but "plant the bastard" in Orlando, FL (wet as hell) AND in Palmdale, CA (Mojave desert). Most ferns, the same but opposite, they may dry and crisp in the cold season, but come summer, if it sustains 75-100 range for an extended period...say 3-4 weeks, they die. A few DAYS at one extreme or another, they're fine. Go to the extremes, they might get a bit of an issue...then snap right back once back in "normal range".


    You can advise shooting for "averages" all you like...the plants didn't develop under consistent averages, did they? They don't get them outside, ANYWHERE, do they? They get a wide range, no matter where. Those RANGES are what they thrive under, not consistency. Fine tuned consistency is only needed where you CAN'T provide steadily variable ranges within the normal "ideal tolerances".
     
  18. good job.  your smart.  your awesome.  you know exactly what your talking about. ;)
     
  19. Nope, still learning the plants themselves...what I know is the physics, maths, and SOME of the chemistry, and am learning, from multiple sources, including formal classroom settings, the precise manner plants themselves function in.

    Which will STILL leave me studying these PARTICULAR plants for years.

    What I DO have is an absolute conviction that what something evolved to thrive under is what it always WILL thrive under, until natural selection changes it.

    Line breeding as is done to fix traits in domesticated animals can only do just that...fix traits. Given enough time, make them distinct and solid enough, it's a new breed. NOT enough to change the conditions they thrive under in any "reasonable" time...took better than 10,000 years of domestication to get from wolf to established wolf-based dog breed. The dogs that thrive under different conditions usually originate from different types of wild canine.
     
    The fastest distinctive breed establishment (consistent genetics) recognized as fully accomplished so far, without genetic modification has been 40 generations in any known complex life form (bacteria and algae obviously an exception, as are all other "breed by division" life forms, who pass exact copies of the parent's genetics on...if the parent has had a mutation of some sort, the offspring have it, but line breeding to fix traits is impossible, just culling, in those cases)...that was Mendel's fruit flies. he fixed the eye color trait quite a bit faster than that, but didn't establish a continuity of a consistent genetic change (multiple fixed traits appearing in all offspring, recessives in those traits driven out) for that long.


    Granted, for indoor strains bred at 3 month intervals, that's 5 years for a completely fixed new strain. A long way from unobtainable, as we've been doing this legally in some places for almost 10 years now, making it easier to openly share plants and seeds specifically for that purpose.

    Also granted that if you're not speaking in terms of a biologist, but, for instance, in terms of a dog or chicken breed for show, what is needed is a published standard of multiple specific traits, all of which must be visible, and three generations where ALL defining traits evidence themselves in EVERY example...the next generation is then "a breed"...which still means enough line breeding to fix multiple traits, and maintain them through 4 active generations. With dogs and a 3 year generation, this usually takes in excess of 100 years. Chickens on their yearly "generation change", it can happen in as little as 14 years, if the changes are insignificant enough, yet significant enough to be noticeable on immediate inspection.
     
    Similarly, with what's popularly termed a "strain" of MJ. 3 generations of absolutely fixed traits not in common with one parent, and others not in common with the other parent, next generation is a "new strain" established.
    \nThat quote from WWU Botany 101 online notes.


    <shrug> We can argue all day, but the thing is, where the technical information exists, for the most part, we're in agreement. I exaggerated a bit with "10%", was called on it, admitted it, showed where and how I got my range figures, and WHY.
     
  20. I don't know why I am being sucked into this... but I challenge all readers to copy and paste any paragraph of this guys comments into google search.  I haven't done so myself, but I expect if I did, search answers would pop up from many different sites. 
     
    Though this does not prove any thing important... it proves the guy is good at googling, using copy/paste, and using nauseating/long-winded plagiarism to prove a worthless point.  The point is... like he said... to make a perfect environment for your plants or as perfect as can be replicated. 
     
    Even newbies at indoor growing can have awesome yields if they focus on 4 very basic principles.  Feed, temp, relative humidity, and light usage/efficiency.   
     

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