Struggling with Humidity in 3' x 3' tent

kermit2692 said:

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

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Did you consider, that for various reasons, of fluids in sealed boxes, the exhaust needs to exceed the intake by 3 Times? That is, a 1" intake needs a 3" exhaust.

An intake filter that is maxed out at 200 cfm, needs 600 cfm on the exhaust or you are pulling well.

And if you buy a 600 cfm fan, can it really do that? Maybe... in a 1 foot, straight run.

why would you want to exchange air 3 times per minute? That's a lil overkill isn't it.

hydrogreen65 said:

why would you want to exchange air 3 times per minute? That's a lil overkill isn't it.

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Why is it over kill?

I have to use my tent for a mother and baby unit cause of the same situation also why have dehumidifier in tent have it in the room outside of the tent it will stop some heat in the tent i used a 600 watt hps and saw 100% a few times

There is no overkill in air exchange, only under kill.

If the air you have available is "better" than the tent air, you must change it as often as you can. I have about 15 cubic feet with 400 cfm. And I can stay balanced with a 300w CFL. If I add the 150w cfl to that, I over heat.

You can just use Calcium Chloride to lower the RH. Set it up as an intake box. Fairly cheap, no-toxic, etc.
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Passive systems like DampRid provide an inexpensive alternative to quietly remove moisture from small areas. These systems are going to be slower, but as a result of their simplicity we can build several variations using the important chemical compound Calcium Chloride.

Calcium Chloride is a very easy to come by salt. Known as "Ice Melt" you can purchase it in 50lbs bags. Also, pool supply stores will sell it as a water calcium hardener. "The anhydrous salt is also widely used as a desiccant, where it will adsorb so much water that it will eventually dissolve in its own crystal lattice water." -wikipedia

You'll need to design a two tier system. You can use things like thin/cheap plastic storage boxes, or 2 liter bottles with the tops cut off and stacked, or ziplock bags and little duct taped ingenuity. Regardless of how you choose to do this step you're going to need a top container that will drip into the lower container.

The upper tier will contain the calcium chloride crystals. It will be open air and, if you can manage it, blowing air over it will increase uptake. You will need to place many pin sized holes in the bottom of the upper tier; this allows the crystals to dissolve and drip into the lower tier.

The lower tier can be empty at the start and it will begin to fill with the dissolved solution. I think a better option than a drip reservoir is to use kitty litter to catch the moisture and lock it up.

Place the system wherever you'd like to in the room, but I would suggest it is close to your intake air. This gives the Calcium Chloride the first shot at the moisture.

When the thing is full of water you simply empty your lower tier, replace your Calcium Chloride in the upper tier, and that's it, that simple.

Now what can you expect from something like this? Well, that all depends on the size of your room, the ingenious of your personal design, your RH (it works better at 50+ humidity), and yadda yadda. So, as a general rule here, it will constantly keep your RH about 10 points lower than the intake. So from 70 to 60, or 60 to 50. Around 40 though it get's tricky, and it won't reduce the humidity much below 30% unless you have several "diy dehumidifiers" in the room.

So, $6 on 4 lbs Calcium Chloride pool hardener and another $6 on a bag of kitty litter, couple of two liters, or ziplocks with some duct tape and you're set.

Good morning, and thanks again for the thoughts and suggestions.
Installed the 6" fan, connected it to the ducting, and ran a second "open" ducting.
My tent now looks like an alien monster.
Switched it on, and within 15 mins, it brought the RH down to 59 % which was in equilibrium with the room.
That's the good.....the bad is that (besides being loud and taking away a big chunk of the free space around the tent) I believe
it created TOO MUCH negative pressure. The sides of the tent were sucked in, puckered even, at least 3 inches. I had a small worry about the integrity of the tent.
The negative pressure was so strong that the width of the tent was equal to the length of the 2 lights and the ducting. When I opened the tent to look there was no
space between the edge of the tent-light-light-ducting-edge of the tent.
The plants, however, looked no worse.
I unplugged the thing at bedtime and left everything else connected.
Shocked this morning, RH is 56 % ! And that is after watering 2 of the 3 yesterday morning.
So, logic would say, the RH was able to be kept the same as the room because of the passive/"open" ducting ??
(I didn't even put back the old fan or the damp rid.)
Plan now is to return the 6" and get a quieter 4". I guess that I still need to move fresh air in and get stale air out.
As far as the formula goes, 3x3x5 is 45 cubed feet, and multiplying it by 3 gives 135 CFM that would be needed; should be taken care of by a 171 CFM fan.
Is that the end of it ? I don't know, and will report back later in the day.


GYF

Under kill. The point you forget is that you put a speed controller on these. You modify the amount suction you need. That changes with temp and RH...the seasons, right?

You want to control, believe me. I have a box of small cheap stuff, all too small. Water and Air Pumps, fans, a stupid little carbon pre-filter, all kinds of undersized stuff. I even have an undersized AC,(but an oversized chiller, I don't even use any more)

And it can't be much of a tent if you worry about suction. These need negative pressure. They are designed for that.

I can't believe you are not listening to me.

Spreaders, (1st pic is sideways) intake from the AC, insulated exhaust at 400cfm to the hot box of the AC. (spray bottle rack, on near right)

Doer what are you talking about?! Pulling well is a bad thing? liquid sealed boxes???wtf lol...are you saying my 275 cfm rated filter is too low or high our I have too little cfm?? Or I should have an 8inch filter if I have a6 inch exhaust?? Please explain

Should I change the arrangement exhaust port <fan<filter<light or how I thought exhaust port<fan<light <filter ...I was trying to avoid a speed controller i've heard reviews that they make your fan louder, take life off of it, and dont work accurately you can turn them and it won't slow down then turn a but more and it slows alot all the while you don't know at what cfm??!! Any validity or a brand you know that is better?

Also my light is 8in Ports while the filter and fan are 6 :/

Hi Doer, and thanks. I am listening , friend, and it was your push on the 6 " that made me get it.
I am now, just trying to figure out what exactly happened.
My primary goal was to get the humidity down to the same level of the room surrounding the tent.
The 6" fan accomplished this, and "no fan" accomplished this.
In my simple mind. if the both can get the job done, a smaller 4" fan would also get the RH down, but it would free up a little space
and be lesss loud.
How about the fact that the width of the tent was exactly as described above, the walls ofthe tent were touching the edge of the light on one side, and the ducting on the other side.
I am not sure what you mean by "speed controller" but I did chat with the guy at the store yesterday, about adjusting the power on the fan and he said I could get an
attachment for $30 that would allow me to adjust the strength of the fan.
I hear you with the changing dynamics of each grow, the seasons, etc. My plan if the RH in the summer got too high was to get the dehumidifer back that I just returnrd, and run it in the room around the tent.
(seeing how easy it was (with no fan) to get the RH the same as the surrounding room.)
What size area are you controlling ?
Do you not think the 4" will get the job done ? or be of any use ? Or are you saying that it might work for the moment, and then, down the road, there is a good chance (? 100 %) chance that I would regret it and go and get the bigger one again ?
I live in Southern Cali, and the climate doesn't change much through the seasons.
Going through what I just went through the last 24 hours, it is so hard to imagine that the 4 " @171 CFM would not be able to get the job done (circulate air and keep RH the same as the surrounding room). I feel like I have to at least try to complete the exercise.
If I am going to keep the 6" I will need to custie up and get the quieter one, and one that is adustable.
Again, I am listening, I appreciate the help, but I don't know that I could go on without knowing what the smaller fan can and can't do
And finally, remind this noob again, about the importance and need to circulate so much air. Is that one of the reason the plants are smallish for 45 days ? Does well circulated air grow healthier/bigger plants ?
It all justseems so much, the tent is 45 cu. feet, and the absolute amount of air needed to be moved just doesn't seem that much.
Just my gut sense.
Thanks friend. Anxious to hear what you have to say.

GYF

Yes you will wind up going back for the bigger one later imo...summer comes your room is hotter or maybe the dehu in the main room brings up temps or you decide to add a carbon filter...I know it cost a bit more and its alot of equipment but when you get used to it you will feel better about having the biggest best versatile equipment you can, and yes 435 cfm i'm that small room will seem like alot and I think since you don't have heat issues and don't have the fan ruining through anything you can definitely ramp it down with a speed controller which hopefully doer can suggest one and lmk if I need one still too

GrowYourFace said:

Hi Doer, and thanks. I am listening , friend, and it was your push on the 6 " that made me get it.
I am now, just trying to figure out what exactly happened.
My primary goal was to get the humidity down to the same level of the room surrounding the tent.
The 6" fan accomplished this, and "no fan" accomplished this.
In my simple mind. if the both can get the job done, a smaller 4" fan would also get the RH down, but it would free up a little space
and be lesss loud.
How about the fact that the width of the tent was exactly as described above, the walls ofthe tent were touching the edge of the light on one side, and the ducting on the other side.
I am not sure what you mean by "speed controller" but I did chat with the guy at the store yesterday, about adjusting the power on the fan and he said I could get an
attachment for $30 that would allow me to adjust the strength of the fan.
I hear you with the changing dynamics of each grow, the seasons, etc. My plan if the RH in the summer got too high was to get the dehumidifer back that I just returnrd, and run it in the room around the tent.
(seeing how easy it was (with no fan) to get the RH the same as the surrounding room.)
What size area are you controlling ?
Do you not think the 4" will get the job done ? or be of any use ? Or are you saying that it might work for the moment, and then, down the road, there is a good chance (? 100 %) chance that I would regret it and go and get the bigger one again ?
I live in Southern Cali, and the climate doesn't change much through the seasons.
Going through what I just went through the last 24 hours, it is so hard to imagine that the 4 " @171 CFM would not be able to get the job done (circulate air and keep RH the same as the surrounding room). I feel like I have to at least try to complete the exercise.
If I am going to keep the 6" I will need to custie up and get the quieter one, and one that is adustable.
Again, I am listening, I appreciate the help, but I don't know that I could go on without knowing what the smaller fan can and can't do
And finally, remind this noob again, about the importance and need to circulate so much air. Is that one of the reason the plants are smallish for 45 days ? Does well circulated air grow healthier/bigger plants ?
It all justseems so much, the tent is 45 cu. feet, and the absolute amount of air needed to be moved just doesn't seem that much.
Just my gut sense.
Thanks friend. Anxious to hear what you have to say.

GYF

Click to expand...

Don't try to imagine. I am a McEiver/Rube Goldberg when it comes to quick experiments.

Yeah, gut sense, but no physics or botany. Here is the deal. All you say would be just fine for that ideal, empty, sealed box, fluid flow. You could breath. Would it keep the heat and humidity in check or just fulfill some 3x, rule of thumb, that is totally meaningless?

But you don't even have that Empty, Ideal Box. You have the reality of your situation. And we are learning and I am doing a tiny bit of coaching, to help my learning.

So, I learned my lessons the hard way. I calculated that a 45 sq foot bathroom could not possible need more that 9000 BTU.....could it???? I mean it can handle a 150 sq ft bedroom, right? Sure, but, the bedroom is much closer to the Ideal Box.

A bathroom running all my equipment that is packed as a 3D puzzle (and still modular) is not an Ideal Box, is it? And inside that is a stuffed grow tent with pumps and lights, not nearly Ideal. So, the 9000 BTU, AC, struggles.

Maybe think of it as a heat/humidity exchange concept. Think of what you want out of there. Do you want fast flow, or sluggish flow over a heat exchanger? FAST transit is almost always better.

OK, the question of plant growth and size, many factors of course, but I am happy with 2" per week.

So, your tent is a labyrinth of small, fractured air paths, OK? At least you hope you are circulating that way. Not in one hole and straight out the other with no circulation.

But, Not Empty, Ideal. With a less vigorous circulation you can get CO2 depletion. In still air, in a dead spot, the leaf uses all the CO2 in the 2 mm around it, in a couple of minutes and just sits there and suffocates.

So, don't think air exchange like what would keep you alive in there. Think heat and humidity EXIT. The faster the better.

I have only one speed controller that I use to balance the AC hot box. It has my biggest fan on top, high amp, 650 cfm. The Tent exhausts with the 400cfm, into the hot box front. There is a carbon filter next to the hot box with a 600 cfm fan and the speed controller.

I set it so, the suction of carbon filter is very light, to INCREASE the transit time over the carbon grains.

Exhaust fan should solve the problem. If you're having problems with humidity you can try using those moisture absorbers.

http://www.bedbathandbeyond.com/store/product/damprid-hi-capacity-moisture-absorber/1017732404?device=c&network=g&matchtype=&mcid=PS_googlepla_nonbrand_cleaning_&gclid=CN6pw4Wx5bsCFaTm7Aod4R0AAw

Alright, another update.
First off though, Doer, are you a Mceiver or a Macgyver ? Don't know the former, but can definitely relate to the latter.
I hope at this point am I done with ventilation. Maybe just a tweek or 2.
Went down to the LHS and exchanged the Hurricane 6" for a Vortex 6", although the CFM is lower, somewhere in the 380 range.
Also got the controller/dial to be able to adjust the power.
Struggled less than yesterday, as I had left the 6" ducting in place.
I patted myself on the back for being able to hang it from the roof. This is huge, as now I don't have to have (literally) 3-4 feet of 6" ducting sitting in the right front corner of the tent.
There is more room on the floor for important things.
It's so quiet, doesn't vibrate, and I love using the knob to control the juice.
Working fine now at 2/3-3/4 power.
The negative pressure is pulling the tent sides in about half as much as the other fan did, and it's not causing the lights to collide.
Please chime I if I have forgotten something or if something doesn't seem right. Should I cover up (nylon/pantyhose) the intake pat of the fan ?
This "feels" so much better.
Thanks and cheers to all.

GYF

No. I'm a McMis-Speller.

Curious, what is this connected to, is that your intake?

^^^-Yes that's the (passive) intake.
One of the tweeks I was talking about was trying to get it into an "S" to block out the light. Hopefully done this morning.

As mentioned yesterday, I am feelng very good about this major adjustment.

Hey FaceGrow. I am very sorry, but I made a SMALL mistake. I found the tent's fan box in the garage just now, and it is a Vortex 4". And again, my apology, it is
indeed 177 cfm...

But, all my other comments are still valid.....as comments.

What I have done for light proof tubes is those black, 4" flex pipe drains. You can bend them into a lot, if you know the secret.

Don't pull it all the way unflexed and then expect it to hold a very good bend. It doesn't fold back well. But, with that in mind, they come collapsed, and can make any bend you need. Then stretch between the bend.

I have one input from the fogger, and the other from the AC.

I tried it with silver flex pipe. Doesn't work. But, the black just drinks the light.