How important is Humidity?

If your extraction I always running you will have a hard time raising humidity as is always been sucked out.so put your extraction on a timer and have It go of every so often to obtain your goal. Not sure on how long etc.etc.as is setup specific but you'll be able to tell. What is really important is keeping it down during flower though so you be fine either way.

 

Bellingham, here. I've done 3 indoor crops in the last two years, fourth just went in to a new, larger tent setup.

Same issues with relative humidity...but consider the idea that natural background humidity up here tends to be high...I don't know if that messes around with meters, or not, but I HAVE noticed that even when my RH meter won't even register for extended periods, my plants still seem happy and healthy, my yields have been respectable for the size I flower at, and the quality has been phenomenal.

I worried about it, and fought it, my first crop, tryign to keep it up at 40%, failing miserably, and stressing...got good flowers. Next crop, ignored it. Crop was actually better. Next crop, just ignored it entirely, got results so good that the portion I brought to the dispensary never made it to the shelf...the manager bought it from the dispensary for his private stash.

 

I use Fox Farms products for nutrients.
For CO2, I use a method I've never heard of anyone else using...but it works like a charm. I was using a 4 by 4 tent inside the house, 4 plants in it...so I cut 4 1 quart milk cartons off about 3/4 of the way up, I leave them in the tent, between each two plants, topping up as needed...every few days, I buy some dry ice, drop it in the milk jugs. Adds moisture to the air while the CO2 "boils", the CO2 turns to "fog" which is cold and hangs low, cooling growth medium (and helping cool the tent), and, as it warms, suffusing the tent properly.


You can calculate what this does to the ppm of CO2 in the tent pretty easily....calculate volume of the tent, measure the volume of the dry ice block, divide big number by small number, which tells you the percentage of the interior volume is now "new" CO2. Finding out how much you want is something each person has a different opinion on, based on whatever they base it on. My rule of thumb is to try and maintain it 10% higher than "normal atmospheric balances" (about 440 ppm, or 0.44%--so a 4 by 4 by 6 tent is 96 cubic feet, and slightly under a half cubic foot of dry ice provides that ratio).

For intake/exhaust...somple..fans are inside the tent, to pull the hot air in, and blow it out through the duct. Now that I went to the big tent with 2 100 watt HIDs in ducted hoods, I ducted the outflow of each fan into the hoods from the middle, then ducted out from the other side of the hoods to outside the tent...sucks the hot air out, blows it over the bulbs (which extends their life by cooling the bulb), creates an underpressure environment, which ensures fresh atmosphere is continuously being drawn into the tent through any available breach.

 

If you have an exhaust fan, don't bother with an intake. Why create a constant windstorm for your plants to weather? How would they fare if they were outdoor plants, grown under a constant wind of that power?

Use negative pressure/underpressure to your advantage...pump the hot air out, let the fact that this creates a low pressure area inside the tent draw air in. Same way a good gaming computer builder will make certain the fans on the back and top of the computer draw air out, and may or may not even bother with side mounted fans that face the CPU heat sink. Pressure wants to equalize, pumping air out in one concentrated area creates significant wind, but pressure differential means the higher pressure air from outside will come in from any possible direction, much more slowly and gently...after all, it's simply trying to replace the volume of air you moved out.

So say you're running a 560 cfm fan pumping hot air out...this means the outside pressure is going to TRY to replace that 560 cubic feet every minute...but it's not limited to an 8 inch tunnel, it has a bunch of vent screens, duct ports, zippers and such aren't air-tight, so each possible penetration point gets air forced in, for a TOTAL of 560 cfm +/-...at much lower intensities.


If you know anything about cars or old school chemical rockets, or know anyone who does, think about what a venturi is, and how it works, because that's the effect you're creating...the fan is the "choke point" of the venturi, the tent itself is the intake funnel. Reason it works is the much wider funnel collects a given volume of air under suction, but as the tube narrows, the air is forced to speed up, because the same volume of air is drawn through a much lower volume area.

 

Freeze bottles of water. 3-4 an rotate daily. Will up the humidity an drop temp.


Sent from my iPhone using Grasscity Forum

 

Not a bad idea...not far from what I do with the water/dry ice, in effect, and much simpler...lol,

But I get gas balance out of mine, so I'll stick with it.

 

it doesnt matter but you'll want a higher humidity for drying

 

She's up by me, in coastal Pacific Northwest country...natural humidity is NOT an issue we have on the low side...it's the high side that kills us...lol.

I fight fungal infections more than anything else, as does every other local grower I know.


But I agree...your atmopheric humidity goes too low during drying, they dry too fast and too much, and you get weed that tastes bad...tastes like hay and a bit of ammonia, sort of.

What I have found works for me for a fall dry up here, is out in a garage or shed in a blacked out hang area for 6 full days, then drop the mostly dried buds into paper lunch bags (about a half ounce per brown paper lunch bag), and drop the bags into a spare cabinet in the kitchen...away from the sink and dishwasher...for another 10-12 days, then drop them in a curing jar, put the jars in the same cabinet for a week or so (best results are 14 to 20 days, in my experience, but a week will work, if you are willing to sacrifice a bit on taste, and anything over 20 days really makes no difference in taste or quality).

But again...that's what works for ME, if you want to use that as a guideline, do. If it improves your quality and effect, keep using it. If you find an even more effective way, share it.