low night time humidity... RH advice needed.

desertmedgrower · Apr 1, 2012

Let me start by saying that during the day my temps / humidity is perfect using a non-sealed system + a humidifier to make up for the arid desert air we have...

That being said at night I don't want to run the humidifier because it creeps up into the 60 % rh range.. Am I ok cutting the humidifier off and running a RH at 25 % humidity at night?

What are the adverse effects if any of running low RH at night time? I have been trying to find solid research on this but to no avail.. Thanks guys.

nebulius · Apr 1, 2012

Fluctuations in humidity from 60% to 25% will likely stress the plants and slow growth . Sometimes leaves curl due to the stomata closing to preserve moisture due to low RH. Plants like stable conditions, so the tighter range you can keep your RH, temp, ph, ect. the less chance you have of stressing and slowing growth.
To increase RH at night I would try putting some buckets of water in your room, some near the fans to help evaporate water. If that doesn't work invest in a good humidifier that has an automatic shut off and that you can set the RH %. You said you live in the desert so you will always be battling RH, for you a good humidifier is a necessary investment. good luck

desertmedgrower · Apr 1, 2012

the fluctuation is more like 45 % in the day down to 25 % at night.... I have not been able to find anything solid on the effects of low night time RH.

catdaddy · Apr 2, 2012

good thread, i was just about to start something similar.
basically i am having the same problem, but instead of rh declining it rises from 40-50 during light hours to 75 when lights are off. im in a tent and would like to know if anyone could recommend a good dehumidifier or another solution for the problem?
thanks in advance.

ttystikk · Apr 2, 2012

Both you guys need a humidistat; one to trip when humidity gets too high, and the other to trip when it gets too low. These are different, and chances are you'll find the right one for your needs in stock in your local area.

Option B, plunk down some coin for a good environmental controller, one that will manage temps, humidity and CO2. Then you'll be set.

desertmedgrower · Apr 2, 2012

Thanks ttystikk, definitely the best advice I have gotten so far...

I think you are right about finding a humidifier with a quality humidistat... that would pretty much take care of all my problems. (not a bad situation to be in really, simple fix it seems) Any advice on a good humidifier that will take care of 100 Sq. Ft or so ? The Kuulaire I have now (it's a garage humidifier or something like that) does a good job on it's lowest setting, but other humdifiers I have seen are pretty weak for my application. Any experience with the 4.5 gallon lasko that says its rated for 3200 sq. ft? It has a humidistat and is in the 90 - 100 dollar range.
Thanks again

ttystikk · Apr 2, 2012

Essick Air Products, Model BFC2000 swamp cooler. I picked up several of them for cheap at thrift stores in the last year. It's about 24" high by 24" wide by 8" thick. Holds over 4 gallons of water. I like it because it is a swamp cooler, so it will reduce temps as well as humidify, AND because it's a wick type humidifier, it will not get hard water spots all over everything like other spray or mister type humidifiers will. It does not have a humidistat built in, and I wouldn't trust one that does. That's a job for a proper environmental controller, or at least a dedicated humidistat. You want precise control of your RH, don't go cheap on your control gear.

desertmedgrower · Apr 2, 2012

Thank you sir, really the best info I could hope for.... what do you do for humidity for veg if you don't mind me asking.... I am running a couple small tents and having trouble controlling the humidity in them as well. (exchanging air as well of course)

desertmedgrower · Apr 2, 2012

Well crap... looking that one up online can't find one... but I actually do have the Essick Cp18 cooler (I guess it's not kuulaire). Looking at it though, I m not gonna be able to use it with an environmental controller or a dedicate humidistat because it starts in the off state on power up ;(

ttystikk · Apr 2, 2012

desertmedgrower said:
Thank you sir, really the best info I could hope for.... what do you do for humidity for veg if you don't mind me asking.... I am running a couple small tents and having trouble controlling the humidity in them as well. (exchanging air as well of course)

I run the unit I mentioned, the Essick BFC2000, It's basically the shape and size of a window box fan, only deeper. It has a manual switch, so controlling it with another device is easy. I'm cheap, so I scrounged in thrift stores and found several over time, none cost me more than $25 used.

http://www.essickair.com/

Talk to customer service, explain you need something without digital controls.

catdaddy · Apr 3, 2012

ttystikk said:
Both you guys need a humidistat; one to trip when humidity gets too high, and the other to trip when it gets too low. These are different, and chances are you'll find the right one for your needs in stock in your local area.

Option B, plunk down some coin for a good environmental controller, one that will manage temps, humidity and CO2. Then you'll be set.

i forgot to mention that im in 12/12. if anything i was thinking i would need a dehumidifier to keep rh down during sleeping hours. what would you recommend?

ttystikk · Apr 3, 2012

catdaddy said:
i forgot to mention that im in 12/12. if anything i was thinking i would need a dehumidifier to keep rh down during sleeping hours. what would you recommend?

In a tent you have some options. One, vent the air, since you don't need to keep up CO2 levels at night. Two, get a standard dehuey, I happen to like my Frigidaire 70 pint unit. Third, and maybe it's a long shot, but some growers think it's best not to vary temps at all between day and night so that approach would help minimize RH swings too.

I run a sealed room and between my girls and the RDWC water, I never need additional humidification. My dehuey runs day and night- not constantly, but it runs at all hours.

true grit · Apr 5, 2012

Ttystikk just nailed it with the easy solution....turn off your exhaust fan or lower exhaust speed during lights off. Does help having a dehuey though because once exhaust is slowed/off the rH will jump.

Easy thing to buy is a Hum-1 controller- around $100 or so and runs both huey and dehuey.

work on keeping a less than 10% shift between photoperiods for optimal growth and allow your plants to be strong enough to fight crap off.

low night time humidity... RH advice needed.

low night time humidity... RH advice needed.

desertmedgrower

nebulius

desertmedgrower

catdaddy

ttystikk

desertmedgrower

ttystikk

desertmedgrower

desertmedgrower

ttystikk

catdaddy

ttystikk

true grit

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