How do you maintain humidity in dry areas?

[olegren]

The area where my tent's at stays in the low 40% range in terms of natural RH. I remedy this in my tent with a humidifier. That works just fine in the early stages where I don't need airflow constantly. I have a timer cycling exhaust 2 minutes every 5 minutes, and the humidifier is set with an inkbird to kick in when it drops below a threshold. The lights are dimmed fairly low, so heat from them is negligible.

But when things start to stink, I need to go to exhaust 24/7; at which point humidify goes sideways fast. The humidifier naturally wants to run all the time, and I just can't keep enough distilled water on hand to keep it going. What humidity it cranks out is going straight out the exhaust. Heat compounds the problem. My Meanwell driver is currently mounted to the back of my QB heatsink. On full blast, it raises temps considerably.

I have read a lot of advice suggesting to instead raise the RH in the 'lung' room -- and in turn the ambient RH will be higher; at which point it naturally follows that the tent will benefit from the same.

So, for those of you in dry areas, how do you accomplish this? A larger whole-home unit? Multiple smaller units? I can only imagine the headache associated with keeping something that large stocked with distilled water. I feel like I must be missing a good solution here. Does anyone have any advice?

Thanks!

 

[Mañ'O'Green]

I run an evaporative cooler on my house and then I have an additional humidifier in the grow space. and yes Distilled water gets expensive but I usually only need it when the plants are babies.

 

[Olderfart]

My low tech solution here last winter was a towel hung into a bucket of tap water with a fan directed at the wet towel. The fan is key, just the wet towel doesn't do the same job. With this setup in a 2x4, humidity was raised by ~20-30%, more than sufficient to get things into target VPD range. The RH in the house at the time was probably in the 40's or lower. It is dry indoors here in the north in winter, sometimes seriously low, but I don't have records. This was with a 6" extraction fan on 24/7, with the fan controller set low.

 

[Mañ'O'Green]

The Aircare has a replaceable filter so you could run tap water and change the filter out when needed?

 

[Death The Cultivator]

RH sensors in the Evaporative humidifier aren't accurate but the humidifiers are good. Don't get a digital one if you plan to you use a controller like the InkBird Humidity version, the digital ones don't restart in case of power failure so the controller switching doesn't work right.

This one holds 4 gallons, filters are cheaper, and it works with controllers.

Do you measure VPD? Might be a happy medium climate that you can reach between seed to flower.

 

[olegren]

Thank you all for the wealth of information! I really appreciate it and am going to use some of this as I get closer to flower.

@Olderfart - I think I'm going to start here. I've read this trick before but had no idea you could net so much extra humidity out of it. It might actually end up being too much, so I may not be able to sustain it -- but am definitely going to give it a shot since it seems like the simplest to implement and maintain.

@Mañ'O'Green - I'll look into snagging one of these if the above doesn't work. My main trouble came around the time I hit flower, but I was dealing with stunted plants and chronic underwatering. I think both contributed to my dryness issues. This time around, I have 4 plants in there. Provided they keep growing well, I expect humidity will be a fair bit higher without further intervention. Otherwise, I definitely like the idea of a larger evaporative unit (particularly with a filter) elsewhere in the lung room.

@FTF_damien50 - Thanks for this tip! I will make sure to take this into consideration if I purchase one. Seems like simpler is better in this case. I do track VPD. So far, I am doing well; but it all falls apart once I have to start running exhaust. I think there were a lot of contributing factors to that last run though, so hoping some of these adjustments can raise my baseline and keep me in a better place for the whole cycle.

Thanks again!

 

[OttoCBD]

There's a popular thread in another forum called "How To Grow The Best Auto Plants" ..I'd link to it but I'm not sure if it's allowed. Anyway, in the OP of that thread it's stated..

"Don't allow temperatures to exceed 30C (86F) as this will hinder growth. At night, stay above 15C (60F). Humidity can be between 20/50 the entire grow, too high and you could loose your entire crop to bud rot.."

I have yet to have an environment dip down to 20 RH but I'm willing to let it happen to see how accurate the above statement is. Everything else stated in the post seems to be right on. Anyway, I just thought I'd put that out there since I see a lot of people (myself included) getting worked up about RH.

 

[olegren]

There's a popular thread in another forum called "How To Grow The Best Auto Plants" ..I'd link to it but I'm not sure if it's allowed. Anyway, in the OP of that thread it's stated..

"Don't allow temperatures to exceed 30C (86F) as this will hinder growth. At night, stay above 15C (60F). Humidity can be between 20/50 the entire grow, too high and you could loose your entire crop to bud rot.."

I have yet to have an environment dip down to 20 RH but I'm willing to let it happen to see how accurate the above statement is. Everything else stated in the post seems to be right on. Anyway, I just thought I'd put that out there since I see a lot of people (myself included) getting worked up about RH.

Thanks, Otto! I attributed a lot of my previous issues to RH, but -- to your point -- it could have been other things. I think, even at extremes, I was in upper 20's. Temps got to some pretty crazy highs (Broke 90F a few times), but I am going to address that by moving my driver external if I can't manage it better this time around.

 

[Death The Cultivator]

Does your exhaust fan have a speed controller? Where does your heat and RH get in full flower will the light turned to max?

 

[Mañ'O'Green]

There's a popular thread in another forum called "How To Grow The Best Auto Plants" ..I'd link to it but I'm not sure if it's allowed. Anyway, in the OP of that thread it's stated..

"Don't allow temperatures to exceed 30C (86F) as this will hinder growth. At night, stay above 15C (60F). Humidity can be between 20/50 the entire grow, too high and you could loose your entire crop to bud rot.."

I have yet to have an environment dip down to 20 RH but I'm willing to let it happen to see how accurate the above statement is. Everything else stated in the post seems to be right on. Anyway, I just thought I'd put that out there since I see a lot of people (myself included) getting worked up about RH.

@OttoCBD RH below 40% will begin to close the stomata preventing transpiration. Without transpiration the plant cannot take in nutrients and eventually will die. RH should be between 40% - 60% at 78°F RH and can go up to 75% at higher tempertures of 85°F. Good air circulation is the key to preventing bud rot. Defoliate the bottom of the plant to let air through. Temperatures <80°F during the last three weeks is integral to getting a good terp profile.