8x4 room - low humidity

[bterzz]

ok so I have a 6" Vortex fan exhausting my room 24/7 with two passive intakes

those passive intakes are sucking in fresh air from outside

If my humidity outside is supposedly 50%, then why would my grow room humidity be much lower, @ approximately 20%...

Can anyone clarify?

I even have a humidifier that i dont think is doing much considering the air is getting exhausted.

help please. Low humidity

 

[TrichyTrichy]

What is the room size?

 

[rabid]

read the title next time...

read the title next time...

trichy, trichy, trichy...Maybe it's.....8 x 4!

 

[pray4pistils]

trichy, trichy, trichy...Maybe it's.....8 x 4!

This is an overly simplistic analysis. If we factor in sociopolitical factors, the effects of global warming, canned food ingredients, and broadcast tv ratings it is obvious that the room dimensions could be double or triple what is clearly stated in the thread subject line.

:wink:

If my humidity outside is supposedly 50%, then why would my grow room humidity be much lower, @ approximately 20%...

Room temperature and relative humidity are inversely related. That is, the higher the air temps the lower humidity you'll see. My guess is that there is a significant difference between the outside and inside temperatures. The only other variable that I can think of is air movement. Swirling air has a lower pressure than stagnant air and that means that it will drop RH, too. However, this effect is tiny compared to temperature.

Anyway, give us some more information.

P.S. It's also possible that your outside RH gauge is defective and not giving you a true reading. I'd measure both atmospheres with the same gauge and compare *that* information.

 

[smoke1sun]

Heres is a lil info on humidity I found While searching for problems with dirt floor crawl spaces.

Give it a read it might help you out some.

http://www.dirt-crawl-spaces.com/crawlspace-venting.html

 

[bterzz]

LOL Trichy, its 8x4, 10 feet tall. The air is getting sucked into the fan at about 7 feet though, leaving 3 feet for a carbon filter i need to attach.

I noticed today when my tempature was around 84 degrees my humidity was actually higher then it was during the night time at 77 degrees.

"P.S. It's also possible that your outside RH gauge is defective and not giving you a true reading. I'd measure both atmospheres with the same gauge and compare *that* information."

I used the same gauge that was in my room and tested it outside. I also tested the same gauge in my bathroom while I took a super hot shower and steam was everywhere. The meter itself was moist but still only read 45% humidity.

I can't see how my growroom would even survive with the moisture that was in the bathroom, so it may be my gauge.

smoke1sun, excuse me but that didn't make that much sense to me..I believe im going to have to re-read it a few times to understand... DOH!

Will this low of a humidity (25-30%) effect the growth of my plants or dry out my buds come flower time?

Thanks for the help everyone.

 

[purpledomgoddes]

unlikely that meter/monitor is working correctly w/ a 45% rh reading after hot shower. if door closed in bathroom should easily climb to 65-85% rh.

low environmental rh requires very adequate irrigation system as the plant(s) will be drawing up root water and transpiring profusely attempting to balance internal+external vapor pressures.

low rh in extremes known to lead to powdery mildew+pests.

relative humidity is an expression of the actual water vapor pressure expressed as a percentage of the maximum water vapor pressure possible under certain air temp+atmospheric pressure conditions.

on cool damp days three ft plants may only transpire a cup of water.

metabolism(growth+fruiting/flowering) generally increases w/ increase in temps (day+night). lower temps/rh slow cell division+force plant to try to surround its canopy w/ the high level of vapor pressure (~24 torr/100%rh/4.65psi) the plant desires.

rh readings are of no significance read in isolation. ambient air temps/root temps/leaf temps/etc are all inter-related.

to remedy rh issue, place bucket of h20 in area w/ air diffuser+small air pump. small comp/20-50 cfm fan close to bubbling bucket. if meter still reads 20%, it has more than likely failed.

edit: if no ill effects observed (whether high/low rh), take note and continue tending to vegetables. best monitor may be the gardener.

 

[HAPPYTREE]

are you using air cooled hoods or open bulbs?????

I run two 600s and vent 24/7 and always have low humidity regardless if tis raining outside.lol( it does come up when it rains i was just saying )

HT

 

[badmf]

Room temperature and relative humidity are inversely related. That is, the higher the air temps the lower humidity you'll see.

Not true!! If you have a rez sitting in the middle of the room and you raise temps it will not change the rh!! More heat can add to added evaporation thus "raising" the rh!! Ever been to Georgia in the summertime? Hot, and yes humid!
On to your "problem" a rh of 20% is no problem, dryer conditions increase trics! Just check your plants medium and make certain that it is in the proper condition. The bucket solution is great too if you "must" raise it. I run 20% in bloom no problem in fact its sparkle city! You said what it is with lights on what is it off?

 

[bterzz]

are you using air cooled hoods or open bulbs?????

I run two 600s and vent 24/7 and always have low humidity regardless if tis raining outside.lol( it does come up when it rains i was just saying )

HT

Two air cooled hoods. Venting 24/7. Low humidity like you. I actually got my humidity up to 47% today with the humidifier running all day.

Badmf - Thats great to hear man. Can i see some pics so you can prove it

 

[pray4pistils]

Room temperature and relative humidity are inversely related. That is, the higher the air temps the lower humidity you'll see.

Not true!! If you have a rez sitting in the middle of the room and you raise temps it will not change the rh!! More heat can add to added evaporation thus "raising" the rh!! Ever been to Georgia in the summertime? Hot, and yes humid!

You are wrong. Hot air is less dense than cold air and thusly holds more water. There's more "space" for it in a given volume. Thus, if you add heat without bringing more moisture in to fill that space... you see a lower indicated RH. The reverse is also true. What happens when temperatures drop when the lights are off? That's right; the RH jumps significantly.

Educate yourself here: http://www.bom.gov.au/lam/humiditycalc.shtml.