Dehumidifier for 2*2*4 grow box

T

Tonino

Member
Hey pals. Anyone has any suggestion for dehumidifying a grow box of 2*2*4? Now I'm in the veg phase with rh of 50%-70% and temps of 26-30C. I'm still good with the rh since i'm in veg. My lights are 90w of household LED bulbs and they're doing great. However for flowering I'm going to switch to a 150w HPS lamp and for flowering I'm going to need to reduce the rh. Any suggestions on how to do that?
The box is located somewhat in open-air so I'll be taking in the free air which is hot and humid in summer.
I know that dehumidifiers like Silica gel wouldn't work probably. Anyone has experience with them?
I was thinking of buying these small humidifiers available for 30 bucks which take 250ml of water each day. Would that work for me?

Thank a lot for advices!
 
nachooo

nachooo

Well-Known Member
Tonino said:
Hey pals. Anyone has any suggestion for dehumidifying a grow box of 2*2*4? Now I'm in the veg phase with rh of 50%-70% and temps of 26-30C. I'm still good with the rh since i'm in veg. My lights are 90w of household LED bulbs and they're doing great. However for flowering I'm going to switch to a 150w HPS lamp and for flowering I'm going to need to reduce the rh. Any suggestions on how to do that?
The box is located somewhat in open-air so I'll be taking in the free air which is hot and humid in summer.
I know that dehumidifiers like Silica gel wouldn't work probably. Anyone has experience with them?
I was thinking of buying these small humidifiers available for 30 bucks which take 250ml of water each day. Would that work for me?

Thank a lot for advices!
Click to expand...
50-70% is ok for most flowering setups…in fact 50 is only ok for the last two weeks imho
The dessicant packs will not work.
The new hps setup will probably reduce the RH...
You can reduce bring down rh ..the last weeks of flowering with some defoliation…
In my opinión, if you increase the air circulation you will be ok...If your Rh is raising, increase the temps to compensate (do not go over 30 C), study the Vapor pressure déficit concept..VPD
I flower in summer with 31 C at the canopy level and 26 C at root level my RH is quite high to allow it about 70-75%. Last two weeks the plants themselves start to produce less humidity.
Remember with high temps you will need high humidity…
If you are using pure indicas they Will suffer more from heat and humidity… but it can be done with proper air movement
If you can Add some CO2 it Will be very beneficial to the plants in order to tolerate the heat
 
Last edited:
T

Tonino

Member
theshape82 said:
You might try something like these hanging desiccant strip or packs, but I'm not sure how you'd go about controlling the humidity with the strips.
The desiccant packs reduce RH down to 50% but won't absorb below that level.
https://growershouse.com/integra-boost-1000g-hanging-desiccant-cargo-dry-6-cs
https://growershouse.com/integra-boost-5-gallon-bucket-with-30-desiccant-packs-curing-solution
Click to expand...
Thanks have you tried them yourself? Do they work?
And anyways if I wanted to spend around 70 box I would buy a decent dehumidifier.
 
T

Tonino

Member
nachooo said:
50-70% is ok for most flowering setups…in fact 50 is only ok for the last two weeks imho
The dessicant packs will not work.
The new hps setup will probably reduce the RH...
You can reduce bring down rh ..the last weeks of flowering with some defoliation…
In my opinión, if you increase the air circulation you will be ok...If your Rh is raising, increase the temps to compensate (do not go over 30 C), study the Vapor pressure déficit concept..VPD
I flower in summer with 31 C at the canopy level and 26 C at root level my RH is quite high to allow it about 70-75%. Last two weeks the plants themselves start to produce less humidity.
Remember with high temps you will need high humidity…
If you are using pure indicas they Will suffer more from heat and humidity… but it can be done with proper air movement
If you can Add some CO2 it Will be very beneficial to the plants in order to tolerate the heat
Click to expand...
Thanks for the information! yeah temps are high but I added another fan also to keep the air moving even more.
So with HPS lamp everything should get better. I will read about VPD, thanks for the advice.
Yeah as I knew about this I got some strain with 60% Sativa in order to be more strong against heat.
Unfortunately with this set up I'm not able to add CO2. I should go a little bit bigger next time.
 
nachooo

nachooo

Well-Known Member
Tonino said:
Thanks for the information! yeah temps are high but I added another fan also to keep the air moving even more.
So with HPS lamp everything should get better. I will read about VPD, thanks for the advice.
Yeah as I knew about this I got some strain with 60% Sativa in order to be more strong against heat.
Unfortunately with this set up I'm not able to add CO2. I should go a little bit bigger next time.
Click to expand...
Keep in mind that HPS will reduce the RH, but a the same time it will raise the temps compared with leds... So to counteract this in summer...you can use the lights on at night , you can increase the ventilation or use a cooltube etc...So keep and eye on temps...
 
Lucky Luke

Lucky Luke

Well-Known Member
Invest in a decent dehumidifier. The cheaper options wont work. $100-$200 buys something with an auto or set function on Ebay that will do a 4 x 4 or more.
 
zypheruk

zypheruk

Well-Known Member
unless your in a sealed room, or extracting back into the same room your wasting money using a dehumidifier, think about it and you will work out why i say this.
What you can do to reduce humidity and is free, defoliate the plants some what and don,t have the medium the plants are in wet. Cover tops of pots if need be. You will be surprised how much that can help.
 
Lucky Luke

Lucky Luke

Well-Known Member
zypheruk said:
unless your in a sealed room, or extracting back into the same room your wasting money using a dehumidifier, think about it and you will work out why i say this.
What you can do to reduce humidity and is free, defoliate the plants some what and don,t have the medium the plants are in wet. Cover tops of pots if need be. You will be surprised how much that can help.
Click to expand...
Has made a Huge difference in my unsealed tent, with a capital H.
 
T

Tonino

Member
zypheruk said:
unless your in a sealed room, or extracting back into the same room your wasting money using a dehumidifier, think about it and you will work out why i say this.
What you can do to reduce humidity and is free, defoliate the plants some what and don,t have the medium the plants are in wet. Cover tops of pots if need be. You will be surprised how much that can help.
Click to expand...
yeah that's what I was thinking as well. The box is located outdoors so the air that gets in is fresh open air and I was thinking if a dehumidifier would work for this situation.
How should I cover tops of the pots? with plastic wrap or sth like that? wouldn't it be harmful to the plants?
 
zypheruk

zypheruk

Well-Known Member
If your grow box is outside and drawing humid air in then there is not much really you can do. The dehumidifier would never keep up with the intake and out take. If you could get air from your home into the box that would help a lot.
But to be honest now that the info of your grow is outdoors maybe some one with similar setup would be better suited to help you.
 
T

Tonino

Member
zypheruk said:
If your grow box is outside and drawing humid air in then there is not much really you can do. The dehumidifier would never keep up with the intake and out take. If you could get air from your home into the box that would help a lot.
But to be honest now that the info of your grow is outdoors maybe some one with similar setup would be better suited to help you.
Click to expand...
The intake is in front of the window and before was taking the air from the room. But since the room is so small and humid and in summer basically hell with open window the rh was going even higher :/
 
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