Dehumidifier help

[Dr.J20]

Hey yall,
So i'm in the middle of a closet grow with an earthbox in a tent. its the beginning of week 2 of flower; my temps are fine but my night time humidity is getting up in the 80s Damn! so my question is this: should i buy a small peltier dehumidifier (2 pint capacity) on the cheap, try to squeeze it into my tent and run it on a timer so that its on during lights out - OR - should i pop a used, larger cap. but much hotter running dehumidifier into the closet but outside the tent and hope that the whole environs get dehumidified without popping dark period temps up too high... so to recap,

Option 1: pray a small peltier dehumidifier works for me INSIDE the tent
Option 2: pray a larger compressor dehumidifier works for me outside the tent but INSIDE the closet

just lookin for input here, any suggestions would be welcome....i am already running two fans inside with a 4" exhaust and an 8" boxfan outside the tent forcing cool air into an intake so I'm not sure if venting is going to be ok and leaving the door to the closet open isn't an option for light proofing reasons
thanks everyone
be easy,
Dr.J

 

[Dr.J20]

Ok, i'm looking at ambient humidities starting to climb meaning that i'm gonna need to make a decision on this real soon... would a mini-dehumidifier using peltier technology be enough to get the humidity in the tent with the closet closed down from ~80% back into the 60% range @ temps b/t 65-85?....my dark period temps are no lower than 65F but my RH is getting high during that period, around 80%...anyone have any experience with this technology? I really can't afford to run a 30pt dehumidifier that draws near 500W for all 12 hours of dk period so i guess theres the decision right there...thanks everyone!

 

[zem]

i have a 250w dehumidifier wood's brand, i have run it with 800w hps 5x5x3 cab and it works great, but i keep it outside blowing through the opening into the tent, cuz inside its motor will raise temps. i only run it after 5-6 weeks into flowering but i run it 24/7 i don't care a lot about what my RH is reading, the dehumidifier will never lower the actual RH more than 6-7% max cuz exhaust is on, but it will be blowing dry air on your buds which effectively prevents mold. i never needed to run it in early flowering, my only concern was mold and a simple oscilating fan can prevent it in other stages of grow. i think you will be at great risk of mold if you only run it night time, i have seen mold in RH 40% without a dehumidifier even with oscilating fans when buds were big enough, and i have never seen mold when it was on even with RH at 55% thats just my experience. my 250w 24/7 adds something noticeable on my electric... how big is your cab? how many watts?

 

[Dr.J20]

Thanks for the reply zem,
I'm doing a cfl/led grow in a grow tent with dimensions 24" x 36" x 62". The wattage is as follows: 1 90w UFO LED, 1/2 90w UFO LED (half panel is out), 1 105w 2700K cfl, 1 65w 2700k cfl, 4 42w 2700K cfl, 2 23w 2700K cfl and 1 65w 6500K cfl bringing a total of ~584w. I'm doing three fem'd white rhino plants in an earthbox (soil with soil-wick that sits in a reservoir.
I don't have the money for running a larger capacity dehumidifier but i bought a small peltier thermoelectric one to see if i can drop the humidity during dark period. my humidity during lights on is right at 59% right now and i'm going to be adding more damprid hangers as well as a silica dessicant to try and keep the humidity as low as i can...So if i have a fan blowing on my girls which is pulling air through a dessicant can (hence dry--or dryer) that should be enough to keep mold problems away? is this what you're saying?

 

[zem]

i don't know about this peltier type, i know that mine can do more than double that cab easy... i gota say in this cab, had you been using a single 400w cmh you would be using 180w less of electric and getting more bud at the same time, not to mention the much simpler wiring and operation of a single light...

 

[Dr.J20]

i don't know about this peltier type, i know that mine can do more than double that cab easy... i gota say in this cab, had you been using a single 400w cmh you would be using 180w less of electric and getting more bud at the same time, not to mention the much simpler wiring and operation of a single light...

thanks zem, of course if i had wanted to go this route it would have entailed more work with a cool tube, ballast, cutting ducting and venting a rented closet...just not in the cards...i was trying to grow a simple starter crop here just to figure out some things but thanks for your input! all the best,
Dr.J

Edit: also, with the cmh i have a feeling the electricity would balance out on the total grow b/c fans running and the work/equp. mentioned above probably would put the set-ups on a par electrically speaking.

 

[zem]

wether you need to cool the cab or not, you still need fresh air for plants to breathe that's if you want to get something worthwhile

 

[Dr.J20]

wether you need to cool the cab or not, you still need fresh air for plants to breathe that's if you want to get something worthwhile

what gave you the idea they weren't getting fresh air? cab's not sealed, closet door open during lights on, fresh air forced into closet during lights off...?
either way
got the dehumidifier and achieved negative pressure inside cab now so we're all good now...thanks for stopping by
peace

 

[48martin]

If you have a small area, I would suggest DampRid as a inexpensive alternative. Takes anywhere from a couple of days to a week or so to start working. I had a similar problem with RH% reaching 80% also. I would also suggest getting an exhaust fan if you dont already and try keeping it on also.
After a week, my RH% does not breach 60%. Seems to be a bit more stable running 50-55% on average. Helped me control and area of 3x3x6.
It only cost me about $3 at Home Depot so it was worth the shot. I got the small cup container version.
Good luck.. Hope this helps

 

[mr.smileyface]

I run a sealed room. My dehum turns off when the humidity is 60% or less. So it wont be on when the lights are on. At night find a dehum that will heat your room to 2c below your daytime temps without your outtake turning on. Your outtake will raise humidity as it is cooling your room. It goes off at night. 70% is good for nighttime temps. Less chance of getting mildew. The reason you get mildew is because you vent out at night time. Think about it. When your RH gets over 80 the leafs have moister on them and the mildew basicly sticks to the plant. This is why you dont run outtakes at night. The best is 12/12 and on a thermostat set to turn on at 32 and stop at 27.
I have my dehums on a humidistat. I use the humidistat conturary to the my hydrometer. give or take.
Anyways good luck

 

[48martin]

Sounds like you really got it dialed in.. Nice..
I wish I could not run my exhaust through the night cycle but it does crawl up if not. The DampRid does help maintain it.
Its been awhile since I have tested it (turning it off to check RH%) but you have some great points.
Thanks
Crossing my fingers

 

[mr.smileyface]

Sounds like you really got it dialed in.. Nice..
I wish I could not run my exhaust through the night cycle but it does crawl up if not. The DampRid does help maintain it.
Its been awhile since I have tested it (turning it off to check RH%) but you have some great points.
Thanks
Crossing my fingers

Get a min/max temp and rh digital meter

 

[48martin]

Got it already. Part of my problem could of been the rain over the last couple of weeks.

I wish I go jump deeper in the pool but my budget or lack of, keeps me in the shallow end.

 

[legallyflying]

The only thing I would ad is low humidity is your best friend for mold resistance and resin production. Also, your dehu demands generally increase as your plants mature. I have two 60 liter dehu's running almost full time to keep my 12 plant 11x8 sealed flower room at >40%

Your plants don't need fresh air at night. There is more than enough oxygen in the air at night and that is what they are absorbing.

 

[mr.smileyface]

The only thing I would ad is low humidity is your best friend for mold resistance and resin production. Also, your dehu demands generally increase as your plants mature. I have two 60 liter dehu's running almost full time to keep my 12 plant 11x8 sealed flower room at >40%

Your plants don't need fresh air at night. There is more than enough oxygen in the air at night and that is what they are absorbing.

Whats your diff. day/night temps
What size pots and how much water per week? Two dehums give off to much heat and thats why your rh is so low.
I dont know about you but my dehums are off during the day. They dont need to be on. I mostly use dehums to heat my rooms at night. Read my last couple posts on here.
The reason your humidity is so low is because you get your room really hot.
Just dont use your outtake to dehum. Try to turn if off before the lights to keep the heat and avoid temp flucuation.

 

[legallyflying]

Whats your diff. day/night temps
What size pots and how much water per week? Two dehums give off to much heat and thats why your rh is so low.
I dont know about you but my dehums are off during the day. They dont need to be on. I mostly use dehums to heat my rooms at night. Read my last couple posts on here.
The reason your humidity is so low is because you get your room really hot.
Just dont use your outtake to dehum. Try to turn if off before the lights to keep the heat and avoid temp flucuation.

Ummm, I wasn't asking for your help dude. My shit is dialed and its not too hot. MY humidity is low because I want it low and therefore run the two dehumidifiers.
It has nothing to do with the temp of the room. If I shut the dehumidifers off then the temp stays the same but the humidity will quickly rise to the 60% range. I don't have an outtake, my shit is sealed tighter than a nuns cunt. Hence the issue of having to deal with humidity.

The point was, as your plants get older and larger they generally put more water vapor in the air. What might suffice now for humidity control may not in the near future. Thats it.

 

[48martin]

Question.... I would of thought it would be a good idea to have circulating air at all times. I am not talking about bringing in fresh air but just circulation and venting only.
Wouldnt that make it more of a hostile environment for molds,mildews, ect..

 

[legallyflying]

Question.... I would of thought it would be a good idea to have circulating air at all times. I am not talking about bringing in fresh air but just circulation and venting only.
Wouldnt that make it more of a hostile environment for molds,mildews, ect..

Yes, you should have air circulating at all times. People that have sealed rooms like myself don't need fresh air as we supply the co2. My hoods are vented but they take from outside the room and dishcharge it outside so its a closed loop so to speak.

Mold spores are everywhere, even in a sealed room. The biggest two triggers fro mold spores to germinate is no airflow and high humidity. That is why its important to keep your humidity low in flower as you can't get air to flow in all the nooks and crannies of your buds. Its not a good idea to have a fan directly blowing on your buds, just circulate the air in the room. My room is fairly small and is jam packed with buds so air circulation is critical for me. My room is 8 x 12 and I have the following fans running 24 x 7.

Two 18" oscilating fans, one on each side wall that blow over the top of the plants..not on them, over them.
One 16" fan blowing air from my co2 gen to the co2 sensor (about head high)
My 8" inline fan is attached to my CF that is hung vertically in the corner. The fan is on the bottom and I attached a 90 degree elbow to blow under the SCROG
Both dehumidifiers have fans , they blow air under the SCROG net.

 

[48martin]

Thanks for the clarification and that is what i was kind of thinking.
Nice First Journal...

 

[Dr.J20]

Its not a good idea to have a fan directly blowing on your buds, just circulate the air in the room.

can you explain this a little more? I mean i'm working with a closet set up so my fans are packed in tight and they can't help but blow directly on the girls...why is this so bad?