Help! 84% Humidity in Grow Box

[drugstorecowboy]

Hi all,

Plywood growbox, lined with mylar, 4'tall, 4' wide, 2' deep ...

Lighting- 4 bulb 2-foot t-5 fluorescents

Temps are at 84 (with CO2)

Humidty is at 84%, too.

The box is sealed as of now.. I was using Damp Rid, but it did not combat the humidty level.

My question: How do I get humidity down in that box? I am in veg and getting mold problems..

The box is in a dam basement which won't dry out no matter how much I run a dehumidifier.

Nearby are a fresh air vent to the outside and a connection to a chimney. I have various squirrel cage fans and inline fans at my disposal..

The thing that bothers me is that I see no way of dropping humidity.. Even if I bring fresh air in from outside and vent up the chimney, I will be at the mercy of nature as to how humid my box is..

Any suggestions?

Thanks,

T

 

[GOATNUTS]

Hi all,

Plywood growbox, lined with mylar, 4'tall, 4' wide, 2' deep ...

Lighting- 4 bulb 2-foot t-5 fluorescents

Temps are at 84 (with CO2)

Humidty is at 84%, too.

The box is sealed as of now.. I was using Damp Rid, but it did not combat the humidty level.

My question: How do I get humidity down in that box? I am in veg and getting mold problems..

The box is in a dam basement which won't dry out no matter how much I run a dehumidifier.

Nearby are a fresh air vent to the outside and a connection to a chimney. I have various squirrel cage fans and inline fans at my disposal..

The thing that bothers me is that I see no way of dropping humidity.. Even if I bring fresh air in from outside and vent up the chimney, I will be at the mercy of nature as to how humid my box is..

Any suggestions?

Thanks,

T

do you have an intake and exhaust fan connected to the box?

 

[newbieb]

would a air conditioner take care of a humidity problem in general ?

 

[drugstorecowboy]

Right now I don't have any fans connected to the box. So it is just one big steaming plywood box, basically. I try to open the door often, and I supplement with CO2, but I'm getting mold and I want it stopped immediately.

I'm not used to grow boxes, however one time I had a basment room which had a hole through the wall to the outside and a fan that sucked air from the room and up a chimney. I did not track the humidty level, but it had to be the same as the air outside. Mold was not an issue on flowers.

So I have the opportunity to do the same with these boxes. That is, I can pull air from 1) the basement or 2) a vent hole in basement wall , through the box, and up the chimney.

My concern is that mold will still be an issue because the humidity will be the same as outside, which is high in the South.

I appreciate the input so far.

-T

PS- I'm used to medium size grow rooms that are sealed and are big enough to run a dehumdifier.. The little box isnt big enough for a dehumidifier.

 

[imnotcrazy]

Humidity in the box should be higher than basement, outside etc. The plants are constantly "breathing" (transpiration), and the size of your cabinet will determine how much they will raise humidity. But you must install some form of ventilation in the box regardless of the fact you are using CO2. Yes CO2 is allowing the plants to stay alive with no ventilation but not having a fan is keeping the humidity WAY too high not allowing the plants to show you their full potential. The lower humidity you can run the more the plants can transpire into their surroundings. The rate of transpiration is related directly to the rate of growth. Get the humidity down to @ 50%. In fact, my cabinet is larger than yours at 6'h x 4'w x 2'd but the bottom 1/3 is for the res and supplies, so I'm just a little smaller than your 4' height and I use a 6" Fantech 200CFM inline pulling through a scrubber and hood and my humidity never goes above 70% when the box is packed like it is now.

 

[MTF-Sandman]

Hmmm...I'm thinking it's time to make a decision...

You either need to duct in some AC to drop the RH and ditch the Co2 or figure out a way to dehumidify the basement. Most likely it's going to be easier and cheaper to do the AC route.

What size dehumidifier did you try in the basement? It's not unusual for it to take 2-3 weeks of running one before it starts to dry out the walls and then you'll start seeing the more dramatic RH reductions that you are looking for.

What is your CO2 system? If you're not keeping the ppm levels up, then it's not going to make a big difference...

 

[drugstorecowboy]

Imnotcrazy- Hey, thanks for the tips. I'm used to bigger rooms which are easier to ventilate.. One question though, you say humidity in your box never goes past 70%.. Where are you pulling your fresh air from? Outside or the interior of your house?

MTFSandman- I'm using a tank for CO2 and a timer. PPMs are sickly high because my flowmeter doesn't really go below 1cubic foot and my timer doesn't go below 15 minutes.. Do the math and you end up with plenty of CO2. Luckily, the box remains cracked and excess CO2 can escape.. The plants are loving that aspect of their lives.

I do have a portable A/C that I could pump cool air in with... I'm going to try birnging fresh air in through a basement vent and exhausting through a 400watt light hood and up the chimney (I'll use the T5 fixture in a veg box later.) I'll put som HEPA filter on the intake to clear the incoming air, as well.

Thanks for the inputs.. Silly me, I thought I could run a sealed box.. I guess I just can't handle that. A sealed room I can handle because you can air cool lights and run a dehumidifier or A/C unit and be rocking that space..

Thanks,

-T

 

[MTF-Sandman]

Hmmm...you've got a portable AC huh? Is it a single or dual hose? You might be able to pull this off after all...

 

[drugstorecowboy]

>>Hmmm...you've got a portable AC huh? Is it a single or dual hose? You might be able to pull this off after all...

Yeah, I have a 9000BTU A/C. It is single hose. This hose is the exhaust. The unit is like a dehumidifier, but larger. It would not fit in the box, practically. I could rig a second hose (I've seen it done somewhere... OG or here..)

Any ideas? In the meantime, I am just bringing in fresh outside air and shotting it out the chimney. At least the air wont be hot and stale in the box..

I see usingthe A/C as the coolest/driest option, but how would I use my portable A/C? In the past, I would have it in the grow room and stick the exhaust in the next room or wherever..

Thanks again.

-T