Struggling with Humidity in 3' x 3' tent

Good morning out there.
I am in the middle of my first ever grow.Day # 49 from seed, 2 Blue Mystic and one Aurora Indica left. Here it is documented as this is my first, https://www.rollitup.org/led-other-lighting/752417-first-ever-grow-hans-led.html
Things were moving along fine until I have tried to get the humidity down, as I hope to flower in 7-10 days.
Long story, everything I have tried has failed, and last night almost killed them all with the heat the dehumidifer put out.


I wanted to try to do his as simply as possible, as my electrical/carpenter skills are terrible.
After much research, I went with:

Tent:Secret Jardin DR-90- 2 chamber tent with the bottom chamber measured at 3' x 3' x 5'
Lights: Hans LED (2)
Medium:Roots organic, and now roots organic/supersoil in 7 gallon pots.
Nutes:none, distilled water and epsom salt.
Fans/intake/etc:none; was hoping to keep it a closed system.....but doesn't seem to be working.
The humidity has been high the entire time, b/w 70-90 %, and goes up after watering, and has increased as the plants have grown.
I have run small non-oscillating fans since seedlings.
So, to try and combat the humidity I have tried, chemical dessicants, damp rid. When that didn't work, I splurged for a dehumidier, http://www.amazon.com/gp/product/B002NXVWGS/ref=oh_details_o01_s00_i00?ie=UTF8&psc=1
Put it in the tent last night, and after 30 mins, temp was >100 and the plants look horrible this morning.
I reviewed all sorts of dehumidifiers, dehumidier/A/C comb, etc.
I start to get palpatations when the words fans, ducting, ceiling, window start to get thrown around. And so avoided the AC/dehumidifer combo as those seem to have a duct of sorts.

So, here's where I am:
I am begining to feel that I am barking up the wrong tree.As the Temp/RH of the room that the tent is in is 70 F and RH 50 % (the temp and RH this AM in the tent were 80/80), all I somehow need to do is get the air outside the tent into the tent.
Maybe, putting in a fan or 2, to do the old "switch-a-roo" will be the answer.
I didn't really research fans/ducts a whole lot b/c I didn't think or want to have to use them.
This is a similar set up to what I have,http://www.greners.com/i/packages/grow-room-packages/grow-tent-packages/stealthgrow-led-grow-room-3-x-3-package.html, and they recommend these,
•Active Air in-line 6" Booster fan
•Ecoplus in-line 4" Duct Booster
http://www.greners.com/i/fans-ventilation-filters/products/inline-fans-blowers/active-air-in-line-booster-fans.html

The question is, how/where exactly to I use/put the fans/duct, as I really don't want to drill holes in the ceiling, or connect it to a window,etc.
Also, as you can see from the pics, the lowest vent on the tent (on the left) is flush with the wall. there are 2 vents on the right which have easier access, but are higher.
Also, I spent alot of time light proofing the vents from the outside, and I am worried about light leaks if I start putting fans in vents, etc.
So, I am struggling with trying to figure out if a simple fan or 2 will solve this problem, or I should consider trying a combo dehum/AC with a single duct that I can run into the surrounding room of the tent.
If the dehumidifer that almost killed them last night had a duct to dissipate the heat, I would connect it to the higher up vent that is not flush against the wall and hope that does it. Are there other options ?

Thanks, so much, in advance,
GYF

Sounds like you are growing in a submarine ...! 7 gallon pots are best for warmer conditions, I'd be using 3 gallon max considerably less dampness around, and a 30% difference in humidity inside and outside the tent ...? sound like your tent is way too small, and or again your pots are way too big, leds? I'm not familiar with your model of LED, but they are well known to be cooler than Mh/HPS lighting, but this is the extreme, I defiantly be installing some 6 inch ducting, and venting outside reguardless of your situation, this should have been resolved at germination....? not a week from bud ...? and keeping the inlet passive, using air from within the room with a 30% difference?

Good luck

Don't use boosters. Just get an axial fan, with the blades 2x the size of the pipe at 400 cfm, minimum, EXHAUST only. Those boosters are junk.


The fan blades have to be bigger than the air feed.

Ok your first goal to have no environmental exchange is not a feasible option. Your plants will not do well with stale air not to mention its impossible to control temp and humidity.you have figured out your solution you need to have an exhaust! Dehumidifier is great to have in case you need it but you can put that in the room not in the tent. Get an inline fan and either just run that as an exhaust or the best option is to run it through your light if you have a cool hood and through the filter which now mitigates smell so you don't need your closed system!

Yea man I live in the desert and I had problems with 5 gallon pots retaining to much water causing not only humidity problems but the water intake slows down when the roots have not enough oxygen.I would most definitely switch to 3 gallon pots makes a world of difference !!!!!!

^ use fabric pots if you don't already...helps airflow to the root zone

The fresh air will also knock down the humidity drastically.I would also install a damper connected to a humidistat.Also remember the air from outside could contaminated with pesky stuff like molds, mildew and mites. Consider some type of air filtration. It could get costly tho.

^ don't worry about all this, you are trying to keep it simple and cheap I gathered and so id pass on adding unnecessary items...just bring in air from the room your tent is in and you will be fine..in reality if mites or mold are in the room they will enter your tent one way or another anyway.

Hi and thanks to all you guys. It's not like I just woke up today. I have been tying for weeks to figure this out, and had bet on the dehumidifier doing the job, which it didn't.

So, spoke to a dude at the hydro sore. +/- help. They also want $100 for a $60 fan.
Asked abut an axial vs. inline, recommended inline 171 cm, and that 400 cfm would "suck in the tent". Made sense to me, and seems like a 4 " hurricane inline fan may work. (as an exhaust only)
Hi Kermit. Thanks for chiming in. Sorry to ask such a basic question, but how will I(passively) bring in air from the room ? ?intake fan ? fan blowing in at one of the vents/ports ? As I said, I worry about a light leak if I have to star opening all these vents.

Mine sucks in the tent. I want that. I use spreaders. I have 400cfm in a 32x32 inch tent.

Leave the vents closed at the bottom..they will still draw in air it will just cut down your cfm rating a bit since the fan will kind of fight the resistance, its nice to open one but light leaks are more important. When you pull the air from the tent that fast through pin holes, closed vents or any other way air can squeak in, that's how you get negative pressure or the tent sucking in as your fan fights to be able to get the air it wants but can't get enough..this causes air to never leave through those vents you see? If air is coming in it can't be going out so now the air only comes out your fan! This contains smell to your tent and your exhaust,adding a carbon filter to the exhaust now keeps the smell to in your tent only for the most part! get in good with the hydro store guy, explain to him you would love to bring him all your business but the fan you need is 65 dollars shipped to your door online, tell him you understand he has to make some money too but your on a tight budget and if he can match that you will buy it right now...he will most likely do it. I've never payed the price on the box at my hydro shop unless its for cheaper stuff or consumables, I let then make their money off me on that stuff I can't get it much cheaper anyway! Hope that helps

GrowYourFace said:

So, spoke to a dude at the hydro sore. +/- help. They also want $100 for a $60 fan.
Asked abut an axial vs. inline, recommended inline 171 cm, and that 400 cfm would "suck in the tent". Made sense to me, and seems like a 4 " hurricane inline fan may work. (as an exhaust only)
Sorry to ask such a basic question, but how will I(passively) bring in air from the room ? ?intake fan ? fan blowing in at one of the vents/ports ? As I said, I worry about a light leak if I have to star opening all these vents.

Click to expand...

The exhaust fan creates negative pressure in your tent and air is sucked in through intake ports, no intake fan is needed as long as your exhaust fan is adequate. To make intake holes light proof just put in some ducting (my tents always had 6") and lay it so it makes an S shape, this will stop light from going through the intake ducting.


Buy your fan on the web, alot of shops are BS but not all. My LHS gives me great deals.

You want your tent to suck in some, if it doesnt then your fan is weak as all get out. Its a fabric wall with no middle support, if it doesnt suck in some somethings wrong or your intake is greater than your exhaust.

I was thinking of the intake Ports and they are square with mesh for me but ya great idea if you need a little more room for air coming in, use the circular exhaust extra port and throw ducting in for light!

Hey, thanks again to all for chiming in. The info is good, the picture is becoming clearer, and a plan is being formulated. Couple more q's. Do you want to have the tent sucked in, a least a little ? will 171 cfm be enough or does it really need 400cfm. Logic says try with just the exhaust fan and see how much air it can draw in through the minute holes all around the tent, and if not getting RH low enough add a passive intake via curling up some duct into an "S" which hopefully does not allow any light in ? I think I will make a generous offer of $80 and see if they go for it. Does this make any sense ?

kermit2692 said:

I was thinking of the intake Ports and they are square with mesh for me

Click to expand...

Yeah, forgot that may be the case with other tent manufacturers. SecretJardin has both square mesh with a velcro cover and a few intake ports (dependent on model) that can be draw-stringed closed.

I use the same concept of the S curve in the intake ducting in my 2kw flower room to bring air in through the panda film divider.

maybe something to try out..


i have been playing with humidity, i live where it gets wettttt.

soo, for a cabinet/tent.. here are some things ive done to lower H..

when i first had problems, i noticed a couple different things that raised humidity. (can be good if you need to)
large pots retaining much much water will get your room humid.. (cure=small pots, less humidity, but more attention to feeding) a little late now, but keep that in mind for when you need to lower/raise humidity.
intake, exhaust.. in all the plants life, you want some source of fresh air, whether it be from window, hole in wall to outside, OR just leaving your bedroom door open.(smaller grows, fresh air is not so much a problem, you can easily use your house air a lot of times.. )

now, you are trying to drop humidity, im not sure if you are using two fans, Exhaust/intake . BUT, say you are using both. i would cut the intake fan out, and only use exhaust ... as well as cover any vents letting air into that veg tent.. just use a lot of exhaust :-]

now for my besttt trick.. i place a small space heater that has a few different settings, low medium, max etc, no exact temp settings, just heat blah blha..

now, i place a baking pan in front of it (to retain heat off the heater) and then place a small clip on fan aiming right at my space heater.. the clip on fan cools down my heaters temp sensor, and keep the air moving 24/7 (ive had problems with space heaters over heating, shutting off, etc.) a metal pan in fron really does a great deal of making that heater more of a beast, and the fan makes sure the heater dont over heat ( i can get my tent/box to controlled temps of 60F to 120F with this setup)


my simple ghetto system that works killer. .



sorry it is sideways. but hope this helps describe what i am doing better..

nowww the cool stuffs. with this combo and i can get a room to 70-80F with humidity as low as 15% .

with a few days of running this, i can dial in when to run a timer, a fan etc..

i like to grow my veggies in a bit warmer heat, 75+ degrees. not pushing over 82 too often.

helps? hope so :]

GrowYourFace said:

Hey, thanks again to all for chiming in. The info is good, the picture is becoming clearer, and a plan is being formulated. Couple more q's. Do you want to have the tent sucked in, a least a little ? will 171 cfm be enough or does it really need 400cfm. Logic says try with just the exhaust fan and see how much air it can draw in through the minute holes all around the tent, and if not getting RH low enough add a passive intake via curling up some duct into an "S" which hopefully does not allow any light in ? I think I will make a generous offer of $80 and see if they go for it. Does this make any sense ?

Click to expand...

That is why I go with a big fan and tight tent. Also, I should mention, much of my suction goes into pulling fog from an outside fogger set up.
I have to add humidity.

What you still are not getting is that you need big air flow, not just a tiny amount that won't suck in the tent walls. You are also battling heat. The hotter the air the more water it holds.

Your plants are transpiring water into the air, also. You are battling CO2 depletion. On a 3 x 3 for Bloom when I setup in the garage, I will use a 600 cfm on the big tent and the small tent at 400 cfm. The A/C external, hot box, with have a 600 and the carbon filter will be 600.

Here is a little hint for you. Those hydro store guys don't shit about it, most of the time. What is their tent production? Most, in my experience, including the hydro store, the web, RIU itself, is just HYPE.

Why? It is an illegal activity that has never been studied, well. So, the "industry" and the "growers" just repeat the same old stuff, of Myth.

But, what has been studied is all Botany.

There is nothing new with this. Treat it like tomato. Look up tent grown tomato.

I should also mention, I cover my tent with foil mylar bubblewrap panels. No sense at all, to allow that black fabric to be exposed to ANY infrared heating.

Ok this may help you understand this...I have a tent that is 4'9" by 4'9" and 7 ft tall...you multiply all those to get your rooms cubic feet so mine is 157.93 now I want to exchange the air in the room about 3 times per minute so I would need a fan that is 473cfm....now in reality I have a filter that needs to be operated at 275cfm tops so I bought a 435 cfm fan that will pull through the light then through the filter father away on the other side of the light, this will knock down the cfm going through the filter but if anybody knows by how much and if ill still need a speed controller that would be great, i'm also ruining through a reducer....I might be remembering the wrong thread but if your going to get the 6 inch hurricane like I have you will be more than fine

just back from the hydro store.
Of course, what "he could do" pricewise, was my max.
$130 for the 6" hurricane,ducting and clamps. Probably could have got it $10-$20 cheaper online, but would have to have waited 3-5 days.
Hydro-store dude, different than the guy I spoke with earlier, looked like a deer in the headlights when I mentioned I might not have any "intake",
although he did mention the "S"ing of the ducting to block the light if I did choose to use an intake.
He also mentioned maybe using the fan outside the tent, to decrease heat.
I think at this point, I will try to hang it in the tent, as it was loud.
Thanks to all for your help, it is much appreciated.
Hopefully, will follow up in the morning.

GYF