Help with tent sweating, humidity

[Moonchild90]

Hey guys,

I just have a couple questions on methods to help lower the humidity in my flower tent. I live right by a river in Pacific Northwestern Washington so that doesn’t help my cause much.

I run my lights at night, from 3 PM to 3 AM. When I get home from work I pop all my vents on my flower tent and it will be physically wet on the inside of the tent. Just a heavy condensation. No water is dripping on my plants though.

It will obviously rise a bit during lights out after I water them but as of right now the highest it will get with lights out is right around 66-68% humidity and after the lights kick on and I pop the vents it will ride anywhere from as low as 53% to 60%. Temps are around 67 with lights out and 76-79 with lights on.

What would you guys suggest? I did a defol on my plants in flower last night but I’m just worried about mold even though I’m still a bit out. I’m day 25 or 26 in flower, I would have to see for sure when I get home.

Any suggestions help! Thank you all so much! This forum rocks!

 

[TorturedSoul]

I don't know for sure what "pop your vents" means, but I suspect that it means to open them, and that - for whatever reason - you're closing them.

Don't do that, lol. If you have a static situation in a sealed box, and drop the temperature, you've just spiked the relative humidity (as air cools, it is capable of holding less moisture). Which may or may not result in condensation...

But you do not have a static situation, you have a dynamic one. Your plants are living organisms; they take in moisture via their root systems - and, eventually, transpire via the stomata (tiny pores in the undersides of their leaves). In effect, you're taking the aforementioned situation and adding to it. Well, your plants are - but just like with little kids, lol, we are responsible for our plants' actions. Raising the RH and, oh yeah, here's a bunch more moisture.

Leave vents open. There's probably no need to run your exhaust fan constantly, but it should be on some sort of timer that activates (cycles) it regularly for a short time in order to exchange the humid air for that which is less humid.

You could "get fancy" with some mechanism to lower the fan speed at night, maybe control it with an Arduino or Raspberry Pi, add humidity and temperature sensors so that it keeps the fan operation to the minimum needed to do the job... Or you could just alter the current timer's settings to kick on for 15 minutes per hour (et cetera) and move on to the next issue.

You shouldn't even see condensation on your grow space walls if you live in a swamp, IMHO.

EDIT: If you are closing your vents during the lights-off period because the space your tent is in is not dark during that time (or you fear that it might not be)... Typing

light trap for grow tent

...into a web-search engine just now got me approximately 7,230,000 results, including ones from this forum (and every other cannabis-related Internet forum).

 

[Moonchild90]

Thank you sooo much!! I don’t even have exhaust system in my tent yet... I’ve been building it all up payday by payday but getting an exhaust system was my plan for this weekend. I was planning on getting a 6 inch fan and running the exhaust up in to my attic. Would you recommend just running it during the dark cycle though? I’m going to look up light catches cause that’s exactly my situation I have going on.

 

[TurboBucket]

Oh boy you have a mess. You absolutely need some air exchange going on. More airflow is never bad. Circulating fans are huge in keeping mold at bay.

If the condensation is forming on the walls at 65% Rh the walls are below the dew point inside. Meaning the air outside the tent is too cold versus your temperature inside the tent

I do not recommend venting into your attic but people do it anyways. Simply circulating it back into the room the tent is in would do wonders for preventing that condensation.

 

[Edzzed]

Howdy, You must be near me, I can see the Pacific ocean (barely) and am 6 miles from the border. I can get you have a humidity issue. You really need to get an inline fan or two with some ducting. There should be some BLACK FRIDAY sales coming up. Try growace.com I run one fan thermostatically, It kicks in at 75 and drops it to 68. The other fan runs off humidity. Set at 70 right now for seedlings. Soon I will be putting in my dehumidifier so I can keep it lower. That dehumidifier has a hose to bucket so can easily dump water. It's also on casters. Read up on my first grow in my sig.

 

[Moonchild90]

I do not recommend venting into your attic but people do it anyways. Simply circulating it back into the room the tent is in would do wonders for preventing that condensation.

Thank you so much for the information! The room that I have my tents set up in is about the size of a bathroom with a bathtub. With it being that small, do you think exhausting just back in to the room would be adequate? I just don’t want to be recirculating humid air. But maybe it wouldn’t be cause the air would be warming up? I was going to have my fan exhaust both my 3x3 flower tent and my 2.5x2.5 veg tent. Do you think that’s too much on a six inch fan? Is trying to exhaust two tents with one fan even a good idea?

Sorry for all the questions!

 

[Moonchild90]

owdy, You must be near me, I can see the Pacific ocean (barely) and am 6 miles from the border. I can get you have a humidity issue. You really need to get an inline fan or two with some ducting. There should be some BLACK FRIDAY sales coming up. Try growace.com I run one fan thermostatically, It kicks in at 75 and drops it to 68. The other fan runs off humidity. Set at 70 right now for seedlings. Soon I will be putting in my dehumidifier so I can keep it lower. That dehumidifier has a hose to bucket so can easily dump water. It's also on casters. Read up on my first grow in my sig.

I think that’s exactly my issue now is not having a proper exhaust system. That’s the game plan for today is to get that going for sure. Just want to be efficient and effective with it as I can. I’ll for sure be checking out your first grow!! Thank you so much for all your help.

 

[TorturedSoul]

You absolutely need some air exchange going on.

You absolutely need some air exchange going on.

Er, that needed to be stated twice .

I do not recommend venting into your attic but people do it anyways. Simply circulating it back into the room the tent is in would do wonders for preventing that condensation.

I wouldn't send warm, humid air into my attic, either, especially in the colder months. Not sure about your local climate or your home's heating setup. But people spend money to heat their house - and, in Winter, some folks have a humidifier attached to their furnace to keep their house comfortable. In houses like that, one might benefit from adding the grow space - its exhaust, I mean - to their HVAC system. @Tead , "down in the swamps," probably wouldn't do that. Perhaps he has some advice for those who have to deal with high humidity, IDK.

For me... Well, it's cold here, and will be colder. Warm air from a grow would be beneficial anywhere in my house - and I would have paid to produce it, after all.

Moonchild90, I understand that you're purchasing components as and when you have the money, and that you have started your grow before having completed your shopping. In the absence of a carbon filter or other restriction, even a box window fan bought from a yard sale for $5 would help.

Light-traps can be simple things (and usually are). Just put some thought into how you attach them to your grow space vents, so you don't have to worry that you'll return home one day to find that one has fallen off and is no longer doing its job.

 

[JKB1989]

I vent into my attic. Sorry I dont see the problem with it. The attic already has its own venting system. Seems to me that fresh air in the attic will mitigate the heated and humid air you are pushing up there. I've been wrong before but I personally think if you're venting into the room that your grow tent is getting its fresh air from that your drastically cutting the amount of fresh air into your tent.

 

[TurboBucket]

Thank you so much for the information! The room that I have my tents set up in is about the size of a bathroom with a bathtub. With it being that small, do you think exhausting just back in to the room would be adequate? I just don’t want to be recirculating humid air. But maybe it wouldn’t be cause the air would be warming up? I was going to have my fan exhaust both my 3x3 flower tent and my 2.5x2.5 veg tent. Do you think that’s too much on a six inch fan? Is trying to exhaust two tents with one fan even a good idea?

Sorry for all the questions!

It really helps to do research before you start growing lol.
So you have two tents and no exhaust fan?

Are we talking trailer house bathroom or mcmansion bathroom? Be detailed and accurate when providing data for us to assist from.

Does that room have a warm air register or a cold air return in it? If no where are the trunk lines? (The big square duct that goes to and from your furnace) What's the temp of that room during lights on. What's the temp in the rest of the house? Humidity? Does your furnace have a makeup air? (A run from the return trunk to outside to bring fresh air in)

I run two 4x4 flower tents on an 8" hyperfan. They are connected to my homes return air duct, all the air from my tents gets circulated into the air from the rest of the house and then redistributed through the supply air. Effectively scavenging the heat from the grows to heat my home in the winter. In the summer it allows me to cool the grows with my Central air unit. Snow on the ground and still not running the gas furnace yet. A 6" should be fine for 15 sq ft depending on what your doing for carbon filters and where your sending the air. I don't recommended anything except a hyperfan but their expensive. Anything to generate some air exchange as tortured soul mentioned will be a huge improvement.

 

[TurboBucket]

I vent into my attic. Sorry I dont see the problem with it. The attic already has its own venting system. Seems to me that fresh air in the attic will mitigate the heated and humid air you are pushing up there. I've been wrong before but I personally think if you're venting into the room that your grow tent is getting its fresh air from that your drastically cutting the amount of fresh air into your tent.

All about air exchange. Most attics don't have a power vent. In that instance yes your fine. If your attic or crawlspace don't breathe well or are non conditioned spaces (No supply air from furnace) then you can create conditions for mold and rot. I've seen it countless times with dryers vented into crawl space.

Venting into the room your growing in depends on most of the questions I just asked. If you exchange the air in the room at a rate that equals or exceeds your exchange from the tent the room conditions won't change much.

 

[Edzzed]

All about air exchange. Most attics don't have a power vent. In that instance yes your fine. If your attic or crawlspace don't breathe well or are non conditioned spaces (No supply air from furnace) then you can create conditions for mold and rot. I've seen it countless times with dryers vented into crawl space.

Venting into the room your growing in depends on most of the questions I just asked. If you exchange the air in the room at a rate that equals or exceeds your exchange from the tent the room conditions won't change much.

I have a thermostatically controlled roof vent in my house. Gets too warm in summer and it will pull hot air out. It was easy to install when we re did our roof. That said, Every house has wiring in the attic for ceiling lights. You can run ducting to the vents or eaves trough area. Use some tape to seal it in place. Fan can be put in attic or in tent but something so it moves air. I have heard you can vent directly into a toilet too so it goes into the sewer system.

 

[TurboBucket]

I have a thermostatically controlled roof vent in my house. Gets too warm in summer and it will pull hot air out. It was easy to install when we re did our roof. That said, Every house has wiring in the attic for ceiling lights. You can run ducting to the vents or eaves trough area. Use some tape to seal it in place. Fan can be put in attic or in tent but something so it moves air. I have heard you can vent directly into a toilet too so it goes into the sewer system.

Venting into drain lines is a big code infraction around here. And nasty lol. Don't ever shut that fan off lol. Not to mention most toilet vents are only 3" PVC.

When you vent outside it's like leaving a window open. All the air you send outside will be replaced with more air coming in from outside. If your discharge air is closer to your desired comfort point (temp/Rh) than the outside air it's more efficient to condition that, than it is to bring in more air that needs more conditioning, (more or less heat or humidity)

Ex. discharge air temp of 75°f 50%rh if it's 40°f 50%rh outside why would you dump all the air you already heated outside only to have to pay to heat the air your bringing in?

If you want to vent outside ideally you should also source your intake air from outside. More or less removing the tents from your conditioned air flow.

 

[Moonchild90]

It really helps to do research before you start growing lol.
So you have two tents and no exhaust fan?

Are we talking trailer house bathroom or mcmansion bathroom? Be detailed and accurate when providing data for us to assist from.

Does that room have a warm air register or a cold air return in it? If no where are the trunk lines? (The big square duct that goes to and from your furnace) What's the temp of that room during lights on. What's the temp in the rest of the house? Humidity? Does your furnace have a makeup air? (A run from the return trunk to outside to bring fresh air in)

That’s exactly what I didn’t do was research on the environment itself. I only thought of the plants and tents, not the room the tents are in themselves...

Yes, I have two tents and no exhaust fan as of right now. A 2.5x2.5x6 that I use for babies and veg and a 3x3x6 tent for flower.

I’ll post some pics of the room itself so you guys can get an idea of the space and where the attic crawl space and window are relative to the tents.

My house is old, it was built in 1910. The only sources of heating are electric panel heaters built in to the walls and a natural gas stove. The only one I use is the stove when I am here during the evening and night.

There is no warm are register or anything for the room. With lights off the room will drop to around 66-68 degrees/66-70% humidity and 72-78 degrees/58-62% humidity when lights are on. The rest of my house runs cold. About 55 degrees on average when I’m not home. That’s just from not having any heat on. Humidity is about 60%.

Maybe I could exhaust from both tents in to my room and have my dehumidifier run for the whole room? The open the window for the warm air? You guys will see everything in the pics.

Thank you all, you rock. Definitely have been learning to get things set up before you start big hobbies.

 

[TurboBucket]

Exactly that's a bedroom not a bathroom lol.

Maybe I could exhaust from both tents in to my room and have my dehumidifier run for the whole room

Correct.

About 55 degrees on average when I’m not home.

This is why your getting condensation on the tent walls the air outside the tent is too cold. Dew point is the point at which atmospheric moisture will condense on a non porous surface.


Adding a dehumidifier into the room will definitely make a big difference. It doesn't simply remove moisture, it lowers the dew point making it harder for condensation to occur.



One thought to consider which would help provide a little bit of airflow through the house would be to vent your tents into the lower floor. You'll end up circulating air from your tent into that living space and pulling air from that space up to your tent room to be circulated through the tents. This way you could pick up some heat from the stove and move it upstairs using only the exhaust fan you already need.

 

[Edzzed]

You can buy a piece of styrofoam to replace your attic hatch. Cut the hole in it and feed some ducting through it. For inside my tent, I have a small space heater which is thermostatically controlled. That's the picture on the left of post #5. The heater from Walmart was what 30 bucks. It does not run all the time. It is there to keep temps from dropping too far. I also exhaust to the roof of the house on the outside up the downspout. and I leave the other bedroom window open2 inches. Very rarely gets below freezing here.

 

[TurboBucket]

You can buy a piece of styrofoam to replace your attic hatch. Cut the hole in it and feed some ducting through it. For inside my tent, I have a small space heater which is thermostatically controlled. That's the picture on the left of post #5. The heater from Walmart was what 30 bucks. It does not run all the time. It is there to keep temps from dropping too far. I also exhaust to the roof of the house on the outside up the downspout. and I leave the other bedroom window open2 inches. Very rarely gets below freezing here.

Allowing an interior room to drop that low is only adding to your heating costs.

Closing rooms off and allowing them to be cold removes your exterior insulation from the equation. Now you have cold air infiltrating through your noninsulated interior walls. The heat transfer is much faster and will require more heating to maintain temps than leaving that room open and allowing the exterior insulation to do what it was installed for.

My 2¢ from a career as a commerical HVACR tech.

 

[Edzzed]

But I like a cold room. Waterbed keeps me warm at night and warms the room somewhat doing it. Also have a box over the floor vents. Heating the house is not a huge deal. Last night I would say it dropped to 7c or 44f outside. Also on EDIT. My room is shaped like a box. It has windows on 3 sides. Most bedrooms would only have two windows at most. You can see stairs going down in the pic.

 

[Moonchild90]

I just got home from picking up a nice 4 inch fan. Going to hook it all up when the lights come on and I think I’m going to vent out my window. That way some fresh air will be coming in to the room as well. I got a speed control for the fan as well. So we will see how it all goes!

I really appreciate everyone’s help with all this! I think getting the fan hooked up will really help it all out.

 

[Tead]

TS brought me 'round by mentioning my name.... kinda like the old 'Devil' adage. It looks like folks have you on the right track. I'll just tell stories instead of giving advice.
I was growing in an outdoor tin shed.... in New Orleans!!!! That's just gonna be a hugely challenging scenario to begin with. I made it work. Ran AC into one tent and then out to the 2nd tent. Had exterior air inlets that pumped thru the sealed light fixtures to keep the lights cool, but kept that hot/humid air out of the tents.
The humidity issue can be battled with large amounts of airflow. Not fresh input air, just blowing the AC'd air around.
Of course, somewhere in the mix there needs to be an air inlet/outlet. Some fresh air will be needed, but not a huge amount really and when you're running AC, you tend not to want to spill all that chilled air out thru a vent. Many times I used the air in the tent as cooling air for my light fixtures and since it dumped outside from the lights giving me a nice amount of outlet flow.

Perhaps he has some advice for those who have to deal with high humidity, IDK.

Meh... you folks have it mostly covered.

Venting into drain lines is a big code infraction around here. And nasty lol. Don't ever shut that fan off lol. Not to mention most toilet vents are only 3" PVC.

Probably 2" for the vent pipe... that's what I usually see for vent pipes in plumbing installs. Don't EVER shut off that fan!
And since when did growers concern themselves with building codes. It's not like any inspector is ever gonna see my setup... so... yeah.... don't concern myself much with actual codes.

My house is old, it was built in 1910

1880. Round Cypress timbers hold up the corners still. Everything else is dimensional lumber... but all the dimensions were different back then. A 2x4 was actually 2" by 4". I do allot of adjustments when I have to work on old walls. It's a wacky world down here.

Adding a dehumidifier into the room will definitely make a big difference

... but will generate a good bit of heat and use nearly as much power as a small AC. Keep that in mind if you go for one.
Plus, those little dehumidifier doodads they sell (some sort of chemical) will not be nearly enough for your needs. Been there, done that.

Now... I gotta get back to work. Pouring a resin kitchen countertop today. Fun!