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Humidity question/issue

BoCoGrow

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My setup is a 4x4 tent in a dedicated 10x10 room.

I'm using a small humidifier, but I'm not able to get the humidity up past 30% because the room's exhaust fan comes on for 15 minutes once per hour to exchange the air. Essentially, the humidity rises to 30%, then the exhaust fan takes it back down to 21%, and then it rises back up to 30% over time before being drawn back down. My options seem to be:

* Do nothing
* Change the exhaust setting to run once every two hours (is that sufficient to ensure the plants have enough fresh air?)
* Buy a new timer that allows settings below 15 minute intervals
* Put the humidity domes back on
* Something else, or a combo of the above

I think the answer is: I have a 440 CFM exhaust fan in a 700 cubic foot room, so it would take roughly 1.6 minutes to fully replace the air, thus I should buy a new timer that allows me to set the exhaust timing to 2 minutes.

What do you think? And if you agree, do you think I could get away with exchanging the air once every couple hours? The tent is 104 cubic feet (again, in a 700 cubic foot room).
 

Jasesq

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I stopped worrying about humidity in my little grow and the plants are fine. If they are drying out water them more.
 

ROSTERMAN

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I use to put 5 gal open buckets of water in with the plants Did help some.
Hard to get it up in the dry winter .
 

BoCoGrow

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Thanks everyone. Since it has been awhile, I've been refreshing my knowledge by reading The Cannabis Grow Bible and various online sources, and they all seem to be quite particular about each environmental variable. But plants do just fine outside of the ideal range (it is a weed after all), and heck, thinking back to my first San Francisco closet grow, I had a 350W HPS light, CO2 emission system, and an oscillating fan, and that was it..no temp or humidity control, no intake or exhaust fans, etc. and the plants flowered. The yield wasn't impressive but I remember being happy with the taste and effects! I just need to chill out and let the plants do their thing. Thanks again for the feedback.
 

ROSTERMAN

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I only really worry when I am in flower if the humidity is above 40%
I get WPM here and need it to be lower most times.
Can always spray mist the plants at lights out too.
 

Sir Bud A Lot

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I have 2 small fans and a 1 1/2 gallon humidifier in my 4x4x86" grow tent it has a hand control switch so I can set the humidifier at 45. It also has a auto switch on it and the tent is in my basement I don't have any problems with humidity any more. It's a LV600LH Hybrid Ultrasonic Humidifier By Levoit I hope that helps
 

docfishwrinkle

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what's your canopy temp? hot air holds more water.

my basement humidity is 20 and my 4x4 tent is kept at an average 80 with swings from 75-80 and is keeping 55% easy. no humidifier wk 4 of flower with 6 plants. water schedule i feel also helps with humidity. how often are you doing that? i water 10% by volume of pot about every other day. if in veg you might have more of a battle but at night is when you really want to pay attention to rh. i do use an environmental controller but still no humidifier in winter. its 5F outside this morning
 

BoCoGrow

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what's your canopy temp? hot air holds more water.

my basement humidity is 20 and my 4x4 tent is kept at an average 80 with swings from 75-80 and is keeping 55% easy. no humidifier wk 4 of flower with 6 plants. water schedule i feel also helps with humidity. how often are you doing that? i water 10% by volume of pot about every other day. if in veg you might have more of a battle but at night is when you really want to pay attention to rh. i do use an environmental controller but still no humidifier in winter. its 5F outside this morning
My seedlings are 5 days old. I have my main hygrometer standing in one of the plants immediately next to the seedling, and right now with the lights off the humidity level is at 32.4%. When the grow room exhaust fan goes on every hour, it will drop the RH to around 25% but the RH recovers.

When the lights are on, the RH goes up to a little over 40%, but it drops as well again when the room's exhaust fan goes on.

I check the leaves a few times each day to look for any signs of distress and they seem fine at the moment.

RE watering, I've been giving each seedling 1.5-2oz of distilled water (didn't adjust PH) 1x or 2x per day using a turkey baster, depending on how dry the surface looks. Last night I have them their first dose of PH'd water with CalMag and Silica Blast.
 

docfishwrinkle

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i thought we were talking plants, but i'd definitely get the rh up for seedlings as it will speed up growth. respiration is critical for fast healthy growth. as it is dry the leaves will shut down pores to retain water and watering soil frequently will only make things worse. proper rh for the 3 stages of growth should be targeted. i like around 75 for seedlings, 65 veg and 55 for early bloom to 40 for late.
 

BoCoGrow

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I have 2 small fans and a 1 1/2 gallon humidifier in my 4x4x86" grow tent it has a hand control switch so I can set the humidifier at 45. It also has a auto switch on it and the tent is in my basement I don't have any problems with humidity any more. It's a LV600LH Hybrid Ultrasonic Humidifier By Levoit I hope that helps
i thought we were talking plants, but i'd definitely get the rh up for seedlings as it will speed up growth. respiration is critical for fast healthy growth. as it is dry the leaves will shut down pores to retain water and watering soil frequently will only make things worse. proper rh for the 3 stages of growth should be targeted. i like around 75 for seedlings, 65 veg and 55 for early bloom to 40 for late.
Thanks to you both. I had ordered a second small humidifier to add to my setup, but just cancelled that and ordered a heavier duty Levoit humidifier.
 
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My setup is a 4x4 tent in a dedicated 10x10 room.

I'm using a small humidifier, but I'm not able to get the humidity up past 30% because the room's exhaust fan comes on for 15 minutes once per hour to exchange the air. Essentially, the humidity rises to 30%, then the exhaust fan takes it back down to 21%, and then it rises back up to 30% over time before being drawn back down. My options seem to be:

* Do nothing
* Change the exhaust setting to run once every two hours (is that sufficient to ensure the plants have enough fresh air?)
* Buy a new timer that allows settings below 15 minute intervals
* Put the humidity domes back on
* Something else, or a combo of the above

I think the answer is: I have a 440 CFM exhaust fan in a 700 cubic foot room, so it would take roughly 1.6 minutes to fully replace the air, thus I should buy a new timer that allows me to set the exhaust timing to 2 minutes.

What do you think? And if you agree, do you think I could get away with exchanging the air once every couple hours? The tent is 104 cubic feet (again, in a 700 cubic foot room).
I think you're putting far too much emphasis on humidity. LOL Been running a setup for several years now and not real sure I ever checked the humidity in there. I never had issues with mold, etc, so it was never much of a concern. The first couple of years during the trial by fire phase, I fretted over every little thing in the grow...until I realized I was stressing myself out for nothing. These things are pretty easy to grow and if I use high quality soil and make sure they have adequate light to force big bud development and keep them watered, they do the rest. I don't even feed mine anymore. The soil easily feeds each plant through the flower cycle and no risk of burning them with chemicals...which I used to be quite good at. I never was brave enough to dive into hydro gardening. If it ain't broke, no need to fix it, right? Best of luck to you.
 

Jakefish

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I'm in hawaii and grow outdoors under an open air canopy. Humidity is always in the 65% - 90% range. Only had one grow go the distance and the rest had to co.e down early due to bud rot starting.... I have 2 18 inch oscillating fans that do a pretty good job pushing air threw the tent but I'm at the mercy of mother nature most of the time.. kinda a bummer but it works out still.
I'm still yielding about 9-10 ounces a plant and can't complain
 

oregongrowguy

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For seedlings try a plastic bottle with the bottom cut off or an inverted cup to increase the humidity for each individual plant. Bottles are cool cause you can use the cap as a vent If needed
 

Bubba

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what's your canopy temp? hot air holds more water.

my basement humidity is 20 and my 4x4 tent is kept at an average 80 with swings from 75-80 and is keeping 55% easy. no humidifier wk 4 of flower with 6 plants. water schedule i feel also helps with humidity. how often are you doing that? i water 10% by volume of pot about every other day. if in veg you might have more of a battle but at night is when you really want to pay attention to rh. i do use an environmental controller but still no humidifier in winter. its 5F outside this morning
It's a fact, hot air holds water better than cold. However, if my humidity rises above 50, I find letting the heat rise lowers my in tent humidity for some reason...to combat both I left the bulb end of my fixture open to the tent, and the fixtures other end out the top, into An infinity 6 inch fan, which then blows into carbon filter.

This usually gives me just under 80 degrees at top of tent, 75 to 78 at floor and humidity around or just under 50, under 40 if I haven't just watered.

Bubba
 

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