humidity?

[WHODAT]

I'm in the first week of flower and my humidity is around 71 percent. This space is co2 enriched. Is it best for me to have a humidifier or is this situation ok?

 

[screwdriver]

i think you may need a dehumidifier. too much humidity and the stomata will close.

 

[BBFan]

I would think you would much rather prefer to use a de-humidifier at this point. Flowering plants prefer aridity, not humidity. Clarke (in MJ Botany) even goes so far as to state that aridity aids in cannabinoid and resin production, though it is unclear whether thc specifically is increased as a result of aridity.

Increased humidity, as screwdriver said, will also decrease the effectiveness of co2 enhancement.

Humidity can lead to mold and rot problems when in flower.

 

[yesmar]

OK, so what humidity range is preferred? Is there a different range for different stages of growth?

 

[Althea]

In my CO2 enriched grow room (CAP ppm sensor, CAP Air 4, compressed CO2) I use a dehumidifier. Now I *own* a humidifier for when Im fighting spidermites as they love that 55% - 65% relative humidity which is also where your plants like it - esp during flowering. I crank it up to 95% humidity in a spidermite battle but thats a whole different issue.

With CO2 running (vent fans, yes? fans on plants too. HID lights have duct attachment points on opposite sides of the bulb and a glass lense sealing off the bulb inside the hood, right?) you should find your relative humidity on the rise fast. My first day I added CO2 mine went from 65% to 80% and the temp went up from 78 to 85F. So as you know the more heat in the atmosphere the greater its ability to retain water - "humidity". The difference between 65F and 85F temp room is almost 2x the ammount of water the air can hold. So you dont want to add more humidity (with the humidifier) you will most probably want to remove it (de-humidifier).

Dont forget to buy a hygrometer so you can tell the current temp and humidity, the min temp and humidity and max temp and humidity in any given time span. When flowering excess humidity (which I define as anything over 65% but definately people agree over 70% is too humid. This will possibly (probably) lead to budrot (botriolysis - I never can spell that right) which is worse than a spider mite infection because for me at least I usually find out it ruined crop when cutting into a perfect cola only to find the whole interior a slimy sloppy greyish mess akin to that stuff that drips out of the mouth of the monster in Alien movies. OK not that bad but the difference is irrelevant as you have to toss out any budrot infested flowers once you can perceive it. It goes through an indoor setup with CO2 and high humidity like a snowplow through your brain cells... Fast, painful and completely destructive.

The CO2 issue with humidity is something you really need to understand. If you have any *any* areas regarding this issue I cannot stress enough how important it is you read up and make sure you get it. CO2 lets your room temp rise and the plants dont suffer (to a point - that point is arguably about 90F compared to 75F optimum in a non-CO2 room. Also you need to control the temp - CONTROL it. Dont let it wander from 68F to 95F as it can do this time of year with CO2. Also dont use CO2 in the final weeks of flowering - it has recently been published that there is evidence that it has a negative effect in those last weeks. Also make sure your ppm is *accurate* (why I shelled out the $ for an infrared top of the line CAP ppm sensor) as too high is damaging, too low defeats the reason for it.

Watch out if its your first time with CO2 - you might be a bit startled by how fast things happen and the increased use of your RO/DI water and nutes (I use an ebb & flow with a res under the trays that hold the plants in rigid plastic squarish 3 gallon containers with Grodan "grow rocks" as a medium. I sort of spaced out the first week I set up the CO2 and didnt go in and moniter once I had it dialed in. I went on vacation for a week. As far as my guestimate goes the plants grew roughly 2.5" per day @ 75F 60% humidity CO2 1500ppm HPS overhead 1000s with light rails. I left and had 12" just turned to 12/12 plants which had just come out of veg. I came home a week later to 30" plants looking droopy and sad - because the 100G res. which was good for 2 weeks sometimes prior had somehow only about 1" of nute/water combo in the very bottom.

CO2 is great but that can be part of its evil side. And trust me you wont need to add moisture to the air unless you live in the Antarctic and are in a 0 - 5% relative humidity environment and so is your grow room.

Good luck. Dont be afraid to ask if I can shed any more light (hehe) on the subject.
Althea

 

[jackson1]

Yes very nice write up but CO2 changes the rules quite a bit to your advantage and most on here aren't using it.

 

[Althea]

Yes very nice write up but CO2 changes the rules quite a bit to your advantage and most on here aren't using it.

You got that right. CO2 takes some serious getting used to and in a complex system like my indoor grow area, with a controller that allows accurate ability to manage an array of environmental factors (+/- 2%-4% error margin is claimed and I have 3 temp gauges and hygrometers to allow for me to verify).

I set the room environment variables at the primary control box. This matches what temp my thermometer gives me, and a backup, and a tertiary backup... And 2% margin of error seems about right - for example if I set the temp to 75F the thermometers may read from 73 to 78F but usually a lot closer to the setting I decided on at the controller box, in this case its more common to set it at 75F and see 74 on one thermometer and 76 on the other...

I added CO2 with a ppm controller which allows me to set the ppm (parts per million) of CO2 and it just sticks it there - if it drops more CO2 is released, once it gets to my target which is the universally approved 1500ppm it halts the CO2 release.

If CO2 is being released the external vent fan has a automatic shutoff control in the environmental control box so my vent fans are plugged into the box as well. It also controls humidity, temperature, the CO2, has a 20 amp fuse and 240 as well as 120 plugs, it has extra plugs for whatever you want to add - fans, ozone, a humidifier, an ionization unit, you name it plus it has a "night" area of plugs where I can opt to plug in something which will not be overidden by the photosensors in the unit. For example the photo sensor detects light and if its dark it will not allow the CO2 to operate. This is because plants dont use CO2 during the dark cycle the way they do in the light. So I save $ on compressed CO2 by having the box know its dark and tells the CO2 controller and CO2 release system that it cannot operate until the lights come back on. Assuming I wanted to waste my CO2 I could plug it in via the "night" zone and it would continue to operate in the dark. Hence the "night" label for that area of plugs. They allow anything to work in the dark.

So all these environmental variables stop becoming hard to manage and can be dialed in to an amazingly flexible and broad scope. And then they stick there like a spidermite on a cannibus leaf. This means (for me) that the benefits of CO2 and as you say in the prior post the way "CO2 changes the rules of indoor growing," becomes even more beneficial as a lot of people who use CO2 havent decided to use the technology designed to maximize the positive effects of CO2 and removes the negatives (higher temp. higher humidity).

I am comfortable estimating a 30% increase in yield and 3 weeks off my plant life cycle. I added an entire extra cycle to my annual grows. Now I can grow 5 harvests instead of 4. Combine that with the extra 30% in yield and CO2 starts looking less like an elite toy or a gadget freaks self-indulgence. It turns CO2 into a self-justifying and valuable part of the whole framework of indoor growing. If one was so inclined it also has a freakishly fast ROI (return on investment) a fancy way of saying it pays for itself fast and from that point it has become free - and from there it keeps going - it took me about a year to pay for all the equipment I added based only on the extra harvest weight and extra grow season. Now it has paid for itself and the extra yield CO2 and the control unit provide are what is referred to as "gravy."

Plus the plants love it, they told me so themselves. In so many, many ways. All good. If you are an established grower and dont need to ask someone stuff like "why are my leaves turning yellow toward the end of the flowering period." because you know its nitrogen deficiency, and you can clone and you dont do all those things I did called "the error part of trial and error" then the next thing I encourage you to do is add CO2 if you are an indoor grower and your space is at least 600 sq. feet. Preferably 800+ but having experienced or seen and asked about CO2 use in everything from a closet o a 50,000 sq. ft greenhouse outside of Amsterdam I can really say CO2 in a grow space is like spinach to Popeye. The question is not "why use CO2," the question is "how can you justify not using CO2 - always assuming you do it correctly. Now if you have two plants or if you grow outside CO2 isnt the way to go. At 25 - 30 plants per grow in a spare bedroom turned into a grow room I just cannot imagine going back to the days without CO2.

Somehow it got a reputation as tempremental and expensive and as a bit of a wild card but I dont know why. Maybe improper use. CO2 is normally 300 - 350 ppm in the air you are inhaling. Globally. I have 5x that much CO2 in my room whenever the light is on. The extra yield justifies it not to mention the way the buds became so much tighter and firmer. I hope this helps someone interested in CO2 but who hasnt made up their mind or who wants it but just didnt know what it does decide to go with their instincts & all the facts about CO2 results.
Al

 

[jackson1]

Sounds good, AL but most here grow for personal use and not profits so we have to look at it as a cost liability vs. a profit generator. I'm happy right now grow without it. If you can get to 75 degrees easy enough that's fine but one of the advantages of CO2 is you don't have to control the temp nearly as much but I agree with 75 even with using CO2 enrichment.

Great info by the way.

 

[Althea]

Sounds good, AL but most here grow for personal use and not profits so we have to look at it as a cost liability vs. a profit generator. I'm happy right now grow without it. If you can get to 75 degrees easy enough that's fine but one of the advantages of CO2 is you don't have to control the temp nearly as much but I agree with 75 even with using CO2 enrichment.

Great info by the way.

Thank you, sir. Yeah I know exactly what you mean in the 'growing for sale or personal,' issue. But I look at it this way - if I could start over I would still use CO2 because in the same space I get more yield and more quickly and my plants are more resistant to disease and pests - CO2 thickens cellular walls as you appear to know a lot about it Im sure you know that. So I get more yield for the same exact setup, my plants are more likely to recover from anything that would effect them negatively. The only difference is the addition of CO2. And regarding cost, I get 20lbs cans filled at a welding supply store for $15

I use about 2 cans a month. My cost is an extra $30 a month for 30% more and better plants. Im also an appreciator, and the same strain grown the same way only with CO2 produces prettier buds - that are more solid and larger and Im sure this is psychological but it seems to even smell better and taste better. I think its just because it looks so much better that my mind says it must be better!

Thanks my friend for taking the time to help me focus my post into a nice little (ok, long) pro-CO2 post based on my setup.

Al

 

[jackson1]

My arm is so twisted now, Althea I feel like your gonna break it, lol... Dude, you love the CO2! I'm sure at some point curiosity will get the best of me and by then I will know all I need to know as I've been reading up on it quite a bit. I'm still learning to just grow let alone throw CO2 into the mix.

You might think about starting a CO2 journal, if you will, in either a thread or even in the DIY section would be even better as I can easily understand what your saying from what you have written so far. Basically, it would be a tutorial on how you use and how you put together your system, what components you used and why you went with what you did, what would you have done differently, if anything, etc in a single thread.

 

[zem]

The only difference is the addition of CO2. And regarding cost, I get 20lbs cans filled at a welding supply store for $15

I use about 2 cans a month.

:2940th_rasta: carrying 20lb cans in/out of my grow is enough to stop me from tryin CO2 :48:

 

[legalize_freedom]

Althea...just curious, how much $ total do you have wrapped up in your c02 system? (if you don't mind)

IMO the only way to add it is to do it right...no cutting corners (which it sounds like you have done) and to do it right isn't cheap.

For my little 4'x4' area...it just doesn't make sense, I just make sure that I'm cycleing in plenty of fresh air.