Relative Humidity Control

[Marko420]

The below is from Meangreen on another site. My question pertains to RH. The grow room is virtually air tight with a portable ac that sucks in air from the outside and exhaust back outside and all ductwork is insulated. Outdoor rh goes from 60% in the morning to 30% in the afternoon but my grow room is averaging 20% more humidity than outside? How can this be? The condensate drain is a steady flow showing that the ac is in fact pulling the moisture out of the air but why is my humidity so high?

Back to the below statements. If I maintain a rh of 50-80% it looks like I increase my chances for females (I'm growing from seed) but I also increase my chances for MOLD.

Any suggestions?

P.S. I'm going to be running CO2 and my grow room is still in the testing stage

INCREASING YOUR CHANCES OF FEMALES
A well maintained grow room with plants growing in optimal conditions will naturally produce more females than males. There are some other things you can do to increase your odds of improving your male to female ratio. These are as follows:
• High nitrogen levels in vegetative growth have shown to produce more females than males. This might be a good to reason to use feeds with a higher l\l to P and K ratio rather than foods with an equal N to P and K ratio. Remember though that plant burn will only lead to stress and this will produce more males and hermaphrodites than females.

• High potassium levels in vegetative growth and flowering tends to produce more males than females. Keeping your potassium levels down is another good reason to choose a food with a higher N than P and K ratio where the P and K ratios are even, or where the K ratio is kept lower than P. Remember though that lack of K can cause plant stress due to this nutrient deficiency and this can cause more males and hermaphrodites to appear than females.
• Cannabis plants grow best under conditions of between 40 and 80 percent relative humidity (rH). In the higher rH range of between 70 and 80 your female to male ratio may increase.
• Cannabis plants grow best at 75 degrees Fahrenheit. If you do not allow the temperatures to increase beyond this you will improve your chances at getting more females than males. If the environment is supplemented with C02 the temperature may be allowed to increase as far as 95 degrees Fahrenheit.
• Using MH lights in vegetative growth will improve your female to male ratio

 

[smoke and coke]

your plants along with watering them will increase your humidity inside the room. i would think you a/c should take care of it, but i dont have an a/c in my op, although i have been considering the idea for a couple years now of getting one.

i have heard other ideas of getting a higher ratio of females, but i feel that the genetic code of the seed is what tells it what it is and you cant change it.

 

[NLXSK1]

Your A/C just isnt enough to take the moisture out of the air.

I run a sealed room and even with my A/C I need to run a separate dehumidifier. Even though the A/C drain line drips constantly the dehumidifier takes 2-3 gallons out of the air a day when late in flower.

You are going to need a dehumidifier as well.

 

[Marko420]

NLX,

Thanks. Now what's the highest RH% you would think is safe from mold, even with adequate ventilation?

 

[NLXSK1]

NLX,

Thanks. Now what's the highest RH% you would think is safe from mold, even with adequate ventilation?

I am fighting to keep mine between 35% & 40%. I have heard that you need to keep it below 60% but airflow is also important and a factor.

 

[Scott187]

i have a dehumidifer and a AC...i have to empty the dehumidifier everyday almost or ever 2 days. My RH is usually 45-50 in flowering...and sometimes goes to 60 for a few hours...but ive never had problems....just stay as close to 50ish you can