Buds growing well, humidity concern...advice?

kryptoniteglo · Dec 22, 2012

Hey Everyone,

My plants are about halfway through flowering and the buds are looking good -- everything's on schedule.

Question: I'm growing in a tent that's open when lights are on and closed when lights are off. When open with lights on, the humidity in the tent is 35%-40%. When closed at night with lights off, the humidity rises to 90%. When lights go back on, it takes about 45 minutes for the humidity to drop back down.

Do I have to worry about mold in the last few weeks? Or does the fact that the RH drops quickly mean mold won't have time to develop?

Any advice will be greatly appreciated!

Thanks!
KG

kvnbeach · Dec 22, 2012

Mold is even more resilient than marijuana. Mold will greow in 30%RH. U have mold u just cant see it, this is why Jorge Cervantes suggest soaking ur plant in H2O2 during harvest. Ur humidity never gets low enough to kill. Also, mold loves the dark, warm, wet, enviroment. U must have some pretty decent air flow to help keep it down, check out this thread How I handle PM

kryptoniteglo · Dec 22, 2012

kvnbeach said:
Mold is even more resilient than marijuana. Mold will greow in 30%RH. U have mold u just cant see it, this is why Jorge Cervantes suggest soaking ur plant in H2O2 during harvest. Ur humidity never gets low enough to kill. Also, mold loves the dark, warm, wet, enviroment. U must have some pretty decent air flow to help keep it down, check out this thread How I handle PM

During the day, there's TONS of airflow and only 30% humidity. It's only at night when the humidity spikes. I have a small oscillating fan in the grow tent that keeps air moving, but I can't have fresh air in there and have it be dark, because the opening for the air would let light in.

I guess my question is will the low daytime humidity of 30% with 80F be enough to keep mold from forming overnight when it's 75F and 90% humidity?

If not, I'll need a small dehumidifier -- and any recommendations for a 3'x3' tent space would be appreciated!

MyPetSkunk · Dec 22, 2012

I would work on getting an intake and exhaust rigged up on your tent. You need to get that same airflow at night. This is one of the main reasons I chose to go tent-less.

kryptoniteglo · Dec 22, 2012

MyPetSkunk said:
I would work on getting an intake and exhaust rigged up on your tent. You need to get that same airflow at night. This is one of the main reasons I chose to go tent-less.

Tentless, unfortunately, is not an option, but I see the advantages. If I ever have a chance to do otherwise I will. But I've ordered a dehumidifier for now. It'll arrive on Monday and hopefully I'll be okay between now and then.

Unless I'm missing something, if I keep the intake/exhaust vent flaps open, I'll also have light leaks, no?

Thanks!

MyPetSkunk · Dec 22, 2012

I don't have any experience with tents, but if there's enough light in the room, then yeah, you will probably get some light in through the vents. That's where ducting can help you. If you run a duct off of your vent, no light should travel through it if setup correctly. From what I gather, most people run an intake and exhaust duct. Their fan is placed where it will extract air through the exhaust, thereby pulling air in through the intake by negative pressure.

I would also think there is someone here who could give you ideas on how to keep your vents open while still cutting down on light leakage, without running ductwork. Somebody step up.

kvnbeach · Dec 22, 2012

I have experience with tents. Mine is 2'6" wide by 6'high. Flowering is an issue. Never I repeat never turn off any of ur fans even when the lights are off. The cold wont kill them. I am Vegging with a 600w HPS bulb, the conversion bulbs suck. I started with a tent and finally figured air flow. I have right now in my tent a Tower Oscilating fan and a 6" clip on fan pointed at the plants, then I also have a 6" fan that I use in my cooltube to keep the bulb cool. It's not an inline fan. Since the tent is in the Garage and our daytime temps are in the low 50'sF I use the heat from the bulb to heat the tent. So thats what I do when i am vegging. When I am flowering, I use a screen and I will have a box fan on the bottom pointed up, plus 3 or 4 6" clip on fans. I NEVER TURN THE FANS OFF! EVEN DURING LIGHTS OUT!

I have another room also. This is not a tent. I have 2 box fans and a 20"oscillating fan and a couple 6"fans. I still need more fans. hahaha

In this pic u dont see it but I usually have a fan underneath.

This was 6 months ago, I have learned ALOT

This gives u a good idea. Ther are other port holes and I will have a 6"fan blowing fresh air in.

This is the updated version

I need more fans!

kryptoniteglo · Dec 22, 2012

kvnbeach said:
I have experience with tents. Mine is 2'6" wide by 6'high. Flowering is an issue. Never I repeat never turn off any of ur fans even when the lights are off. The cold wont kill them. I am Vegging with a 600w HPS bulb, the conversion bulbs suck. I started with a tent and finally figured air flow. I have right now in my tent a Tower Oscilating fan and a 6" clip on fan pointed at the plants, then I also have a 6" fan that I use in my cooltube to keep the bulb cool. It's not an inline fan. Since the tent is in the Garage and our daytime temps are in the low 50'sF I use the heat from the bulb to heat the tent. So thats what I do when i am vegging. When I am flowering, I use a screen and I will have a box fan on the bottom pointed up, plus 3 or 4 6" clip on fans. I NEVER TURN THE FANS OFF! EVEN DURING LIGHTS OUT!

I have another room also. This is not a tent. I have 2 box fans and a 20"oscillating fan and a couple 6"fans. I still need more fans. hahaha

View attachment 2452249In this pic u dont see it but I usually have a fan underneath.
View attachment 2452250This was 6 months ago, I have learned ALOT
View attachment 2452251 View attachment 2452252This gives u a good idea. Ther are other port holes and I will have a 6"fan blowing fresh air in.View attachment 2452253 View attachment 2452254This is the updated versionView attachment 2452255I need more fans!

Ok. Heard you loud and clear. Tonight I put in an extra fan to keep air moving around. The dehumidifier is arriving Monday. Thanks!

Bakatare666 · Dec 22, 2012

kryptoniteglo said:
Hey Everyone,

My plants are about halfway through flowering and the buds are looking good -- everything's on schedule.

View attachment 2452074 View attachment 2452075

Question: I'm growing in a tent that's open when lights are on and closed when lights are off. When open with lights on, the humidity in the tent is 35%-40%. When closed at night with lights off, the humidity rises to 90%. When lights go back on, it takes about 45 minutes for the humidity to drop back down.

Do I have to worry about mold in the last few weeks? Or does the fact that the RH drops quickly mean mold won't have time to develop?

Any advice will be greatly appreciated!

Thanks!
KG

Keeping the fan(s) going 24/0 and watering right at lights on will help, also make sure if you're using drip pans they are empty.

kryptoniteglo · Dec 23, 2012

Bakatare666 said:
Keeping the fan(s) going 24/0 and watering right at lights on will help, also make sure if you're using drip pans they are empty.

Okay...interesting. The plants don't drink water at lights out, only during lights on. So when I "put them to bed" around 6pm, I check the res and usually bring it up to the right level then. Otherwise there's about 2 inches of exposed root. There's still plenty of root underwater, but there is about 2 inches exposed.

But very little actually changes during lights out -- they don't drink water, they don't take nutes and the PH doesn't change. All that action happens during lights on. I always thought after such a busy day I should put them into a balanced res environment as soon as possible.

But it sounds like you're saying that since the plants aren't drinking anyway, no need to top off until the morning when they'd actually start using the water? Is that because less water in the tent in general will create less humidity? I'm just curious.

Bakatare666 · Dec 23, 2012

Sorry man, didn't catch that you were hydro.
I thought you were soil.

joe blow greenthumb · Dec 23, 2012

Here's a cheap fix that I did. I used cheap 10/20 buck rectangular fan from Walmart. It runs 24/7 as my intake. Unless you have super bright light in the room it won't get thru the slits in fan enough to register on plants. Is the same size as your tents intake Ports.

kryptoniteglo · Dec 23, 2012

joe blow greenthumb said:
View attachment 2453196Here's a cheap fix that I did. I used cheap 10/20 buck rectangular fan from Walmart. It runs 24/7 as my intake. Unless you have super bright light in the room it won't get thru the slits in fan enough to register on plants. Is the same size as your tents intake Ports.

Thanks Joe! If it hasn't negatively impacted on your grow, then I'll assume I can try the same thing. Thanks!

kryptoniteglo · Dec 23, 2012

Bakatare666 said:
Sorry man, didn't catch that you were hydro.
I thought you were soil.

ARGH!!! Just kidding. I was all excited about the "don't water at night" trick!

But thanks to everyone here for the helpful advice. I have a dehumidifier coming and I'm trying to improve the airflow situation without allowing light leaks.

Buds growing well, humidity concern...advice?

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