Let me know how the bigger dehumidifier works… Still looking for a reliable one. Every one I’ve found on Amazon is followed by someone talking about “it barely works” or something similar. I need something that slaps water straight out of the air.
will do 
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I can’t speak for or against any particular brand, however, placing a dehumidifier inside a tent is rarely effective due to the exhaust vent.
If you are running an exhaust you’re likely cycling the air faster than a dehumidifier will be able remove the moisture from the fresh air that is entering the intake.
Your results are going to depend on the moisture content of the larger (lung) room the tent is in so start by controlling RH there to get humidity on point.
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makes sense. is it normal though to have the tent RH circa 20% higher than the ambient? that’s what i am seeing so wondering if my exhaust is strong enough it seems pretty weak but i have no reference to compare it to.
anyway cheers for the advice
With a 20% variance between tent and room, and being unable to lower RH in the tent, your exhaust system may well be underpowered as you mentioned.
Are your bottom intake vents open and clear?
I run a 5x7 room in a basement. A 16" wall fan, 6" intake fan ducted to 95 sq. ft. lung room conditioned to 72° F/50% RH, 6" exhaust ducted to unused area of basement keeps temp and humidity in the proper range with the AC Infinity Controller 67 adjusting fan speeds as needed.
In my case adding the 6" intake fan was the key. I first thought to go to a bigger exhaust fan, but I had an extra 6" Raxial fan laying around so I added it to the intake duct and set it to run 1/4 speed. Now the exhaust fan runs at a lower speed and temp and humidity are spot on.
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Interesting. Am in a 3x3 with exhaust but no intake fan, just open vents. When I added an intake fan the tent started ballooning so i removed it.
exhaust fan is just a standard basic inline, will have to look at it in more detail to see if it is up to the job. was supplied as part of a “starter kit” by the growshop so I just went with it.
however i still have the intake laying around so am going to test adding it back in.
thanks for the info!
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Stoney said negative pressure in the tent is good so I am following his advice lol. I have exhaust but no intake like your setup, 3x3 too
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Sounds like your intake was running at too high a speed . . . I run a constant 1/4 speed on my intake, exhaust is always pulling harder.
In my case the intake fan just helps get the air moving in the right direction and allows me to run the exhaust at a lower setting and still maintain the environment.
No real need for an intake unless your exhaust isn’t up the job, or you want to ease/share the load on your equipment. I first added mine when I was considering a larger exhaust fan than the Cloudline T6, had a 6" Raxial laying around so I stuck it on the intake duct at a low speed setting and no more problems.
As far as negative pressure, I do maintain slight negative pressure by running the exhaust at a higher speed than the intake.
A question of my own?
Concerning negative pressure, other than odor control, do you know what the benefits, if any, are to the plants?
I’ve done some very limited research and all I’ve found are pretty generic statements about making it easier to control climate. And I’ve found those that say negative pressure prevents mold, and the next says positive pressure prevents mold.
While I run an HVAC type filter on my intake, a positive pressure would seemingly do more to help prevent any type of airborne pathogens entering the grow space than negative.
I’m just looking for a reason to justify not spending more money. Not sure the reason behind the benefit of negative pressure
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small update, added a more powerful exhaust fan and put the previous one as the intake fan, as before i just had the vents open. was interested to see if it made a difference. currently at 64% which is around an 8-10% improvement.
had wet spots on some leaves this morning and saw i had overnight RH of around 74% so defo time to bring it down before i get issues.
dehu arrives on monday which should allow me to ratchet it down as i get into later stages of flowering.
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nice will keep that in mind but i have no way of controlling it right now. i have two basic inlines, one slightly more powerful that the other.
what i’ve done for now is put the intake on the humidity controller, so when it gets above 60% is kicks in. just testing really. keeping the exhaust going 24/7. but even though RH is high, my vpd is on point as temps are around 80F.
so not too worried but defo want to bring it down as i get further into flower, and drying. or at least have more control, right now i am stuck at around 65% so more control is essential going forward.
hopefully the dehu sorts it, last option will get a better exhaust…
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That dehumidifier may very well heat up the space. I have had that happen in my bedroom.
They need and all in one deal… like a 2-way circulation system all automated so you can “set it!, And forget it”! And I always love getting a cheap camera so I can always see the room whenever, wherever. Controlling everything from your iPhone makes it so much easier, however it may take the fun out of growing for some.
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Keep your tent in negative pressure for the entirety of your grow for best results. Negative pressure is beneficial to your plants as it makes it easier to control and maintain temperature, humidity, CO2 levels, and other contaminants because the hot, humid air is extracted from the tent quickly and constantly at the same rate. This allows for a stable environment within your grow room and avoids any risk of mold or mildew forming on plants.
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Dude, you are 100% correct ! My apologies guys! I finally found that article eventually!!
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ok so the dehumidifier finally arrived and has been running a day or so. grow room is about 10m2 and the dehu is capable of removing 16l per day. I have read that the dehumidifier should ba capable of taking out at least what you put in, ie if you water with 10l then the dehu should be rated at 10l per 24hr min.
its managed to get the room down to 45%RH with the tent coming down from 65-70% to about 55% so defo has made a decent difference so far. that is with it set to 45% and I think it can go down to 35% so that should be sufficient for all stages of the grow.
only slight concern is that the tent is still running 10-15% higher than the room so may get a more powerful exhaust but that can wait for another day.
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Can you link the one you decided on? Still have to order mine, I’m looking at one but want options
yea sure, it was this one:
Is in Spanish but you get the idea. Depending on your room size (this one is rated to 70m2 but I would take that with a pinch of salt) and how much you water, your avg RH etc you might want to go to 20 or 30l ratings.
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Sorry to bother, but do you know why one of my baby plants has two leaves (one which seems to be cupping, the other wilting), with a tiny burnish mark on one? There was some algae on the soil so I’m airing it out and put a little cinnamon sprinkled around it. I’m guessing that cup isn’t drying out as fast as it should?
Thanks so much!
And my lemon auto seems to look a little funky no?
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Hey @Austingreenest
Apologies for the delay in responding…
First I’d recommend to make your pot containers darker! The roots shouldn’t be getting light at all… They’re drooping “clawing” and I suspect there’s NPK imbalance because of that. I’d maybe spray paint it black, or use black refuse plastic to wrap around…
First do that, I’m sure it’s the problem and let’s check it from there. I like black because it absorbs & holds heat better… 