humidity

[babymonkey]

hi guys
ive switched to 12/12 for flowering just 2 days ago,i switch on at 10am & switch off at 10pm,when the light & fans etc. are switched on the humidity is around 50 which is good i think,but in between 10pm - 10am while the lights are off,my humidity goes upto 80%...

my question is ...with the humidity going aqll the way upto 80,is this going to be damaging to the plants?,also if it does what can i do to bring the hunidity down to around 50%

thanks all

 

[BBFan]

Hello babymonkey-

Even 50% humidity is a little on the high side. Flowering mj thrives in an arid climate. Also, too much humidity can lead to bud rot.

Have you tried running your fans 24/0? That might help with the humidity, and good air exchange is always beneficial.

How low do the temps get during lights off, and how high do they get with lights on?

A dehumidifier, while costing a few hundred bucks, may be a good investment. My experience though is that they tend to increase temperatures.

Good luck to you!

 

[babymonkey]

Hello babymonkey-

Even 50% humidity is a little on the high side. Flowering mj thrives in an arid climate. Also, too much humidity can lead to bud rot.

Have you tried running your fans 24/0? That might help with the humidity, and good air exchange is always beneficial.

How low do the temps get during lights off, and how high do they get with lights on?

A dehumidifier, while costing a few hundred bucks, may be a good investment. My experience though is that they tend to increase temperatures.

Good luck to you!

hi BBFAN,thanks for reply

i havnt tried running my fans 24/7,but i might give it ago as you got me worried about bud rot.

temps with the lights on ,is about 76 - 80 degrees.
temps with lights off,i know goes down to 58 degrees

i have tried a dehumidifier,as you said it does raise the temp up,also it seem to raise my PH in the feed by 0.5 a day,this was the main reason i took it out of the tent

when you say about keeping the fans running,i have an 8 inch extractor taken air out of the tent,a 6 inch extractor bringing air into the tent,also an osculating fan blowing over the top of the plants.

do i have to keep all of them running or just the osculating fan ?

thanks

 

[BBFan]

Babymonkey-

Can you run the dehumidifier during lights off? Your daytime temperature is near perfect, but 58 degrees F is just a little on the cold side.

How was it affecting your ph though:confused2: I've never heard of that, or did I misunderstand?

As far as the fans, can you check the rh outside your tent? If it's lower, just use the intake and exhaust fans and that should take care of the humidity. If the outside rh is higher, try just the oscillating fan.

Good luck!

 

[nouvellechef]

I run fans 24/7 and De-humidifier is set it and forget it at 40% on top of a rez.

 

[docfishwrinkle]

temps with the lights on ,is about 76 - 80 degrees.
temps with lights off,i know goes down to 58 degrees

i have tried a dehumidifier,as you said it does raise the temp up,also it seem to raise my PH in the feed by 0.5 a day,this was the main reason i took it out of the tent

when you say about keeping the fans running,i have an 8 inch extractor taken air out of the tent,a 6 inch extractor bringing air into the tent,also an osculating fan blowing over the top of the plants.

do i have to keep all of them running or just the osculating fan ?

hey BM sounds like you might need a space heater for that tent. 58* is a lil chilly. shoot for mid 60's.

how did you come to find out a dehumidifier raised your ph? never heard this before just curious. you are maybe doing hydro?

yes IMO leave all fans running.

 

[dman1234]

Just a thought but are you getting an accurate humidity reading
80% seems very vey high.

 

[babymonkey]

hey BM sounds like you might need a space heater for that tent. 58* is a lil chilly. shoot for mid 60's.

how did you come to find out a dehumidifier raised your ph? never heard this before just curious. you are maybe doing hydro?

yes IMO leave all fans running.

thanks m8,ye when i was using my dehimidifier my ph kept rising,now ive taken it out my ph is stable,i didnt really change anything else so im just assuming it was the dehumidifier that was rising the ph as im doing hydro

the only problem i have with running all fans of a night is the tent is in my bedroom & the fans make too much noise

hopefully after another solution

 

[babymonkey]

Babymonkey-

Can you run the dehumidifier during lights off? Your daytime temperature is near perfect, but 58 degrees F is just a little on the cold side.

How was it affecting your ph though:confused2: I've never heard of that, or did I misunderstand?

As far as the fans, can you check the rh outside your tent? If it's lower, just use the intake and exhaust fans and that should take care of the humidity. If the outside rh is higher, try just the oscillating fan.

Good luck!

hi bbfan
i only have 1 thermometer to check humidity which is inside my tent,but im going to buy another 1 in next 2 days,by what you mentioned above i hope the humidity is higher outside the tent so i can just leave my osculating fan on,instead of all fans

thanks m8

 

[babymonkey]

:d

 

[Rosebud]

My humidity is 33 and temp is 73. I am in great flowering now and wondered it I should up the humidity? Help.

 

[Funkfarmer]

Do whatever you can to get the humidity down, I had high humidity with lights off and it led to powdery mildew and it was hard to get rid of.

 

[babymonkey]

just a couple of questions on whats the best temp & humidity figures

1)in veggie stage with lights on whats the best temp for temperature & himidity ?

2)in veggie stage with lights off whats the best temp for temperature & humidity ?

3)in flowering stage with light on,best temps for temperature & humidity ?

4)in flowering stage with lights off,best temp for temperature & humidity ?

hopefully people can give there own opinions & answers on the above 4
questions & maybe make it all clear for everyone else to read as i always see people asking for these figures about humidity & temp all over the forumn

thanks all

 

[BlueNose]

1,2)75 deg. F , 60-70%
3,4) 75 deg. F , <40%
(temp. high<day> 80F), (low<night> 70F) is my goal no matter what stage of growth with 75 F being optimum.

I use a small heater at night to keep heat up


*Solely my opinion*- I like higher humidity during veg. My thought is that the plants grow a bit better when the leaf and trunk/branch surfaces are able to interact with moist air rather than taking all the required moisture from the soil. This is completely my opinion and very unproven so take it with a grain of salt....I haven't had anything negative happen though.

 

[Rosebud]

According to Marijuana Horticulture by Jorge Cervantes:

"The best relative humidity range:
Vegetative: 60-70%
Flowering 40-60%
clones 80-95%"




The moisture holding capacity of air doubles with every 20 degrees F (10 degrees C) increase in temperature.




I haven't read about lights being on or off matters. The temperature does matter with regard to humidity. I hope this helps. After reading this I misted to bring mine up to bring it back to 40%. This is the only book I have, I don't know if everyone agrees with him or not..We will see.

 

[babymonkey]

1,2)75 deg. F , 60-70%
3,4) 75 deg. F , <40%
(temp. high<day> 80F), (low<night> 70F) is my goal no matter what stage of growth with 75 F being optimum.

I use a small heater at night to keep heat up


*Solely my opinion*- I like higher humidity during veg. My thought is that the plants grow a bit better when the leaf and trunk/branch surfaces are able to interact with moist air rather than taking all the required moisture from the soil. This is completely my opinion and very unproven so take it with a grain of salt....I haven't had anything negative happen though.

hi m8
thanks for the info,what type of small heater do you use at night to keep the temps up ?

cheers m8

 

[BlueNose]

just a cheap two setting 900/1500 watt with a digital temp setting. You can get them at Target, Home Depot etc.

I have pretty good airflow so I set mine at 77F and it keeps my temps about 70-72 on cold nights(roughly 30-40F)

 

[babymonkey]

just a cheap two setting 900/1500 watt with a digital temp setting. You can get them at Target, Home Depot etc.

I have pretty good airflow so I set mine at 77F and it keeps my temps about 70-72 on cold nights(roughly 30-40F)

thanks m8
definatly going to be investing in 1 of those

thanks

 

[BBFan]

1)in veggie stage with lights on whats the best temp for temperature & himidity ?
78 deg F / RH 50% - 70%

2)in veggie stage with lights off whats the best temp for temperature & humidity ?
65 deg F / RH 50% - 70%

3)in flowering stage with light on,best temps for temperature & humidity ?
78 deg F / RH 20% - 40%

4)in flowering stage with lights off,best temp for temperature & humidity ?
65 deg F / RH 20% - 40%

hopefully people can give there own opinions & answers on the above 4
questions & maybe make it all clear for everyone else to read as i always see people asking for these figures about humidity & temp all over the forumn

thanks all

Just my thoughts. MJ prefers humidity during veg and aridity during flower.

MJ does not require a dark period during vegetative growth. Light independent reactions occur during lights on or lights off.

Ideal temp for photosynthesis for many leafy C-3 plants (like mj) is around 78 deg F without supplemental or enriched co2.

 

[PUFF MONKEY]

58f at "night" is the reason for the humidity jump..try a cheap space heater set to 65f and run your ventilation 24/7.