How temperature and humidity relate

[Arctic Bowl]

Boveda Humidipak

Lol we are off to the rain forest to get a truck load of them. Ok, maybe not a truck load but we are stalking up on them.

 

[TheFertilizer]

Not to really shift the topic, but I don't know about those Boveda packs. Everyone says they make the bud soft and pliable? Kind of sounds a little too wet for my tastes, I stuck a hygrometer into my jar to see where it's at at the dryness level I like it at, and it's 35%. I don't know they said most people prefer 62%, I always did feel like weed I got from the dispensary was too wet... People call it "slow burning" but I always felt more like it just took longer to get a good hit. Different strokes I suppose?

 

[Dogwash]

As far as i understand, molecules DO NOT expand when heated - they vibrate faster - most materials do expand due to heat, air included - this expanding is due to the extra vibratory rate

Thanks for the thread though - very important topic

 

[Arctic Bowl]

As far as i understand, molecules DO NOT expand when heated - they vibrate faster - most materials do expand due to heat, air included - this expanding is due to the extra vibratory rate

Thanks for the thread though - very important topic

Thanks DW, I was trying to explain it how it was taught to me many years ago. How it was explained was that the molecules did expand and contract as the temperature increased or decreased. I'll take a pic of how it was shown to me, made sense to me and gave me a visual reference to how things worked. If this is not how it works I stand corrected however, the visual worked for me. Pic in a few min

Blessed Buds our friends and be well

 

[Arctic Bowl]

This is pretty much ho it was drawn out for us, cooler temp smaller molecules and higher RH, warmer molecules larger and lower RH.

Blessed Buds our friends and be well

 

[Dogwash]

When air (for instance) is heated, it has more energy - the molecules remain the same molecules but just behave differently - they bounce around more - the material appears to expand but the actual molecules have not changed, only their behaviour has changed due to their higher energy state

That being a pedantic but important detail IMHO

You're right about the practical side of it - warm air can hold less moisture

Many thanks for the thread, helped me improve humidity and improve growth in tent, our bottom line eh

 

[Arctic Bowl]

Thanks DW, you are correct and if the information aids in us gaining better understanding and better control of our environment then we all win. We are new to the growing of everyone's favorite plant here and have had tons of help from many members to get us going. We just wanted to try and give some information back to the community here in a way that is hopefully understandable.

Blessed Buds our friend and be well

 

[Pennywise]

This thread has been really helpful, its caused me to stop and think about my temps.


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[Dogwash]

I've been proper obsessed with temp & humidity recently but my work is paying off! Internodal spacing 1/4 to 1/2 inch mostly, proper bush not a tree!

Keeping down temp differential between daytime & nighttime has been key - day temp around 29, night temp around 21 - one small oil filled heater set to a tickle inside tent, another small heater just outside, with thermostat set to come on at 19C so air coming into tent aint too cold - heaters come on a timer 15 mins after lights go out

Humidity around 50% with several bowls of water using towels as wicks on tent floor which has raised humidity by around 10%

Philips daylight 315w lights are awesome too, such quality rays off em

Have had to buy UV ski goggles as regular UV sunglasses just weren't cutting it on eye protection front

Looks daft but avoids the dazing eye glare whiteout

 

[TheFertilizer]

I have tried the wet towel thing and it does nothing for my tent, I had to order a fan controller, as well as a humidifier. My humidity is getting all the way down to 16%.

Do you guys have those hygrometers from AccuRite that has the little "OK" "Low' and "High" symbol in the upper right hand corner? Anyone know what that is supposed to mean?

Had to put my little sprouts in a humidity dome until the controller and humidifier get here, the top soil got dry so quick at 15% RH.

 

[Arctic Bowl]

I have tried the wet towel thing and it does nothing for my tent, I had to order a fan controller, as well as a humidifier. My humidity is getting all the way down to 16%.

Do you guys have those hygrometers from AccuRite that has the little "OK" "Low' and "High" symbol in the upper right hand corner? Anyone know what that is supposed to mean?



Had to put my little sprouts in a humidity dome until the controller and humidifier get here, the top soil got dry so quick at 15% RH.

We were having similar issues in our tent and found that setting the fan to its lowest speed and setting our humidifier up to its highest setting of 65% we could keep our tent around 50-55%. Just a trail an error thing until you get it where you want it. If we need 60% our fan has to be off, removes to much air even on lowest setting for humidifier to keep up with the air changes in the tent. Our humidity gets nasty low up here during winter as well and it takes a bit to get it sorted out.
The high,low, ok readings I believe are the highest temp/humidity, lowest temp/humidity its recorded, the ok, is humidity I think and if it drops too low it will say dry and too hi it will say wet. Device should have a clear or reset button for monitoring your hi/lo.

Blessed Buds our friend and be well

 

[bliz]

I have tried the wet towel thing and it does nothing for my tent, I had to order a fan controller, as well as a humidifier. My humidity is getting all the way down to 16%.

Do you guys have those hygrometers from AccuRite that has the little "OK" "Low' and "High" symbol in the upper right hand corner? Anyone know what that is supposed to mean?

Had to put my little sprouts in a humidity dome until the controller and humidifier get here, the top soil got dry so quick at 15% RH.

afaik, it's a human comfort level saying the rh is hi/ lo.

 

[TheFertilizer]

We were having similar issues in our tent and found that setting the fan to its lowest speed and setting our humidifier up to its highest setting of 65% we could keep our tent around 50-55%. Just a trail an error thing until you get it where you want it. If we need 60% our fan has to be off, removes to much air even on lowest setting for humidifier to keep up with the air changes in the tent. Our humidity gets nasty low up here during winter as well and it takes a bit to get it sorted out.
The high,low, ok readings I believe are the highest temp/humidity, lowest temp/humidity its recorded, the ok, is humidity I think and if it drops too low it will say dry and too hi it will say wet. Device should have a clear or reset button for monitoring your hi/lo.

Blessed Buds our friend and be well

Yeah this one weirdly is supposed to measure over like a 36 hour period or something. The instruction manual was confusing... I just know that the high of 46% didn't happen until I put it in the dome. Before it was topping at like 25%

It makes sense with everything you're explaining. The house is not a vacuum, so all that frigid winter air is coming in and getting heated immensely. LIke 50 degree temperature differences at the extreme lows of the season, and on top of that the air outside may not have much moisture to begin with.

Getting that fan speed down would help a lot of things I believe. For one thing, I can literally feel a draft coming in from my outlets because the air circulation is creating a negative pressure in the room my tent is in because it exhausts into an adjacent room. It's actually so dramatic that there is a little a noticeable pull on the door to keep it open when I come in and out.

afaik, it's a human comfort level saying the rh is hi/ lo.

Ahh okay I thought I remembered reading that in the instruction manual.

One thing that's very strange.... I see inspects in my tent from time to time, but never alive. They're always just lying dead on the tent floor, and I don't really use any significant pesticides besides neem and just bug barriers and I've never seen anything like that. I think the air flow and humidity levels as well as radiant heat from the light just make it completely inhospitable for insects. Not necessarily a bad thing...

 

[dauzer]

Im having some major issues with the RH in my room with lights off. I have followed all the posts and im staring to understand... But i still don't lol. I understand what RH is but i understand how it affects the moisture in the room

So here is what im experiencing...

With lights off, my hydrometers read 99% RH while the temps drop to about 14 - 16º C. Now when i walk into the room it feels dry, no condensation on the walls, no water droplets nothing. Iv been to countries where the humidity is high and you can actually feel the moisture. Its sticky and wet. But this is not how my room feels even though the hydrometers are reading 99% RH. How can this be ??

Is 99% RH an issue even though the room doesn't feel wet ? I'm afraid to use a dehumidifier is case it sucks what moisture is there out and dries out the plants.

Im a bit confused about the whole thing so my explanation might not make sense. So please let me know and i will try elaborate more.

Thanks in advance

 

[Dogwash]

Hi, i think that's too cold for the night phase - if you put a small heater in there set to come on when the lights go off you should keep the temp around about 20C in veg, 18C at night in flower - the humidity will show as lower

I am having similar issues & have noticed the RH climbs to 80 during the night phase

I'm keeping them around 19C in their night phase - almost two weeks into flower - gonna drop it to 17/18 in their night phase next week - been keeping it 19 ish during stretch to encourage smaller internodal spaces

 

[dauzer]

Hi, i think that's too cold for the night phase - if you put a small heater in there set to come on when the lights go off you should keep the temp around about 20C in veg, 18C at night in flower - the humidity will show as lower

I am having similar issues & have noticed the RH climbs to 80 during the night phase

I'm keeping them around 19C in their night phase - almost two weeks into flower - gonna drop it to 17/18 in their night phase next week - been keeping it 19 ish during stretch to encourage smaller internodal spaces

You reckon raising temps at night will drop the RH ? I can pick up a small hearted bar tomorrow and hook it up to a temp controller. I'm after buying a new hydrometer which displays the due point so I'll will monitor tomorrow after lights come back on.

When your room gets to 80% do you feel any moisture in the air ? That's the only thing that throws me. If the air is not moist I don't see why it would be an issue


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[Weaselcracker]

AB if you're still around. I'm back to ask this question again, sort of. Maybe in a slightly different way.
This is a similar question. I asked on another thread, but got no answer. Here is the conversation.

The other guy said-

"The water capacity of air doubles with each 10°C rise in temperature. What that means is if you have 100% RH at 6°C and add a heater to bring it up to 16°C, the RH will drop to 50%. This assumes that no moisture is added to the air, something unlikely in a grow environment."

I asked-

"If all the moisture in a room is suspended in the air and no more is being added- what is the effective difference between an RH of 100% and one of 50% at those temps. None? Other than that the lower temperature situation with an RH of 50% is closer to saturation/dew point?
Does that make sense? Kind of stoned. Lol!
Like what if your jar of bud is 60% RH at room temp and it drops ten degrees? Then what -how is the situation in the jar different?"