Switching to Sealed Room Exp Growers HELP!

[SAMCRO]

the 2 Dehumidifiers never let the room go above 60%. when i had 1 70 Pint dehuey the levels were as high as 75%. never had any mold problems ever. my memory recall therm and Rh meter tell me where im at for the 24 Hr period with highs and lows. the second dehuey for me help keep ithe RH in check. id rather have a monster big one instead of 2 of them. dri-ez type deal. but waiting to upgrade later.

 

[monkeymun]

No- I meant it exactly as I said it; if temperature falls with a constant amount of moisture (think about it; in a sealed room, where's it going?), relative humidity rises. FAST. What's 55% at 80 quickly becomes 80%+ at 65. This is why you need a dehumidifier in a sealed room and when you'll need it the most.

Your quotation above is correct, but not the right application for describing what happens as the room cools overnight. What that saying means is that relative humidity will fall as temperature rises, with a constant amount of moisture suspended in it. Relative humidity is an expression of the percentage moisture in the air relative to its capacity. So if temperature rises, and the air increases its ability to hold moisture, then the relative humidity falls... follow me?

Those who actively cool their nighttime environment can inadvertently accelerate this process, by pushing humidity up before their dehuey has time to work. This leads to high RH, ideal conditions for the spread of mildew and others.

Where's it going? It condenses. But you have a good point, before condensing, it obviously has to reach a saturation point (100% RH).

 

[ttystikk]

Where's it going? It condenses. But you have a good point, before condensing, it obviously has to reach a saturation point (100% RH).

Right, and think about the consequences of 'rain' in your grow room. Aside from the obvious trouble with electrical equipment these are also deal environmental conditions for molds, mildews and fungi. Yummy...

Keep in mind that it doesn't even have to get to 100% to be an environment conducive to these pests, either. 75-80% and temps in the 70s will do just fine.

 

[Canvas]

Just to toss in 2 more cents, the other factor that really affects mold is circulation.

None of you have mentioned how many circulation fans you have going, or how you set them up.
I had great success in an 80cm tent using at least one 6" fan per plant, 6 fans for 4 plants worked a charm.
Now that I have a bigger, 120cm tent, I need 16" fans, possibly more than one;

moreover, the fans need to be set up such than they complement each other, rather than opposing.
By setting up a vortex, the air kept moving, and there was move overall movement, compared to having the fans blowing in opposing directions.
This did alleviate a mold problem I had, (with a weak ass plant) with no change in RH, which was less than 50 anyhow.

Peace

 

[ttystikk]

^^^^ Props to Canvas- circulation is key. This is the mechanism by which the plant respirates, regulates its temperature and absorbs CO2. If the air is stagnant, then not only are ALL of the above compromised, but the plant is vulnerable to attacks by molds and mildew.

 

[monkeymun]

Definitely, circulation is necessary. Stagnant air and CO2 buildup both lead to problems with mold.

 

[shaker1]

I've been looking into running a sealed room as well and would like to know if there are any books or indepth, detailed articals on the subject? (besides on here). But on a small scale (3x3 or 4x4). The room is 7x7x7 w/ slant ceiling but I'll only have 1, 1000w light. Want to hear about pros and cons, ect....I get the feeling that going from a vented room to a sealed room is like going from soil to hydro...lol...need to know as much as possible before making the jump!

...""Those who actively cool their nighttime environment can inadvertently accelerate this process, by pushing humidity up before their dehuey has time to work. This leads to high RH, ideal conditions for the spread of mildew and others....""

@ttystick....I've had my a/c on 24/7 since the heat hit here...should I just have it on the "Dry" mode at night? Temps at night at times are 80+ w/ high humidity. But I also have a 409cfm inline venting the 2.5x2.5x7 space 24/7 as well..lol...lil' overkill maybe? Too much? Day temps are 80-85 w/ my 400w.

 

[tedsprogz]

You mean the other way around, right? The warmer air is, the more water it can hold.

Yes so the RH would rise as the temp falls.
RH is a ratio of water vapor(partial pressure) to how much the air an hold(saturated vapor pressure).
as the temp falls, the amount of water it can hold(the 2nd number) decreases, increasing your RH.
1:4 = 25%
1:2 = 50%
see how that works?

EDIT: need to read the whole thread b4 i reply lol. tyystick already covered it lol.

 

[monkeymun]

:D

 

[LexLuthor]

NO! This guy's advice here is a recipe for fungal pathogens to attack your crop. Just because temperature falls doesn't mean you're safe from the problems associated with high RH. It's called relative humidity for a reason; it rises as temps fall. You will want to use a dehumidifier to actively manage this aspect of your indoor environment.

In general, if you feel the need for a scrubber in the room, then do it. Others say it's unnecessary, or it's a sign that your room isn't sealed well enough. You already have the CO2 supplemented; what is to be gained by pushing all that air through a carbon filter?

In a sealed room, you need to firmly control the temperature, humidity, CO2 content, and everything else. That's the whole point of a sealed room. External venting is useless at best, and a potential avenue of discovery at worst. so SEAL it, already... :cool:

As long as you keep the RH below 70% your not gonna get pathogens due to high RH, relative humidity means the humidity is relative to the temperature, so 90 degree's F at 80% RH has more moisture in the air then 70 degree's F at 80% RH. The hotter the air, the more moisture it can hold, that is what relative humidity (RH) means. So his RH rises at night, no big deal, most people have growrooms where the RH rises 10-20% at night, its normal.

 

[ttystikk]

As long as you keep the RH below 70% your not gonna get pathogens due to high RH, relative humidity means the humidity is relative to the temperature, so 90 degree's F at 80% RH has more moisture in the air then 70 degree's F at 80% RH. The hotter the air, the more moisture it can hold, that is what relative humidity (RH) means. So his RH rises at night, no big deal, most people have growrooms where the RH rises 10-20% at night, its normal.

At first glance, this advice seems reasonable. Trouble is, it doesn't stand up to closer scrutiny; for one, if your night time temps drop by more than 5 degrees, then you'll see a pretty dramatic rise in RH- why? Because RH rises exponentially as temperature falls, not in a linear fashion like you might expect. For two, running RH in the 70s during bloom is about 15-20 points higher than educated consensus. So, if RH rises by 20% at night, and it started at 70%, that would be... 90%. A recipe for guttation and budrot.

If you're going to run a sealed room, either use AC so it can indirectly dehumidify (which is imprecise and leads to more problems), or get a dehumidifier.

 

[ttystikk]

I've been looking into running a sealed room as well and would like to know if there are any books or indepth, detailed articals on the subject? (besides on here). But on a small scale (3x3 or 4x4). The room is 7x7x7 w/ slant ceiling but I'll only have 1, 1000w light. Want to hear about pros and cons, ect....I get the feeling that going from a vented room to a sealed room is like going from soil to hydro...lol...need to know as much as possible before making the jump!

...""Those who actively cool their nighttime environment can inadvertently accelerate this process, by pushing humidity up before their dehuey has time to work. This leads to high RH, ideal conditions for the spread of mildew and others....""

@ttystick....I've had my a/c on 24/7 since the heat hit here...should I just have it on the "Dry" mode at night? Temps at night at times are 80+ w/ high humidity. But I also have a 409cfm inline venting the 2.5x2.5x7 space 24/7 as well..lol...lil' overkill maybe? Too much? Day temps are 80-85 w/ my 400w.

Hey, what's shakin'? Sorry it took me until now to answer this; I didn't see it 'til now.

Most AC units will reduce humidity as they operate; passing warm moist air over the cold coils will condense water quite nicely. The problem comes in when you try to regulate this effect to maintain a specific humidity level; since you're using what amounts to a saw to drill with, you can count on chasing one issue after another. One example; at night there is no heat source to warm the room and activate the AC, which means it doesn't run and therefore doesn't dehumidify- right when you need it to the most! While it isn't always cheap, getting a dehuey to solve high humidity problems is getting the proper tool for the job.

 

[LexLuthor]

At first glance, this advice seems reasonable. Trouble is, it doesn't stand up to closer scrutiny; for one, if your night time temps drop by more than 5 degrees, then you'll see a pretty dramatic rise in RH- why? Because RH rises exponentially as temperature falls, not in a linear fashion like you might expect. For two, running RH in the 70s during bloom is about 15-20 points higher than educated consensus. So, if RH rises by 20% at night, and it started at 70%, that would be... 90%. A recipe for guttation and budrot.

If you're going to run a sealed room, either use AC so it can indirectly dehumidify (which is imprecise and leads to more problems), or get a dehumidifier.

My RH is below 70%, not at 70 and it fluctuates between 55-70% in the summer and I don't have a dehuey. If its 90% RH which is above 70, then its too high, like I said. Based on my exp. anything below 70% will be fine. Keep a clean room and people won't have problems from RH hitting 70% once in a while, I never said 90%. Keep RH below 70% and your safe.

 

[ttystikk]

My RH is below 70%, not at 70 and it fluctuates between 55-70% in the summer and I don't have a dehuey. If its 90% RH which is above 70, then its too high, like I said. Based on my exp. anything below 70% will be fine. Keep a clean room and people won't have problems from RH hitting 70% once in a while, I never said 90%. Keep RH below 70% and your safe.

Clearly, being imprecise leads to all sorts of misunderstandings. Precision in one's thinking, discussion and work style is the difference between a hobbyist and someone serious about their craft- in this game or any other.

 

[LexLuthor]

Clearly, being imprecise leads to all sorts of misunderstandings. Precision in one's thinking, discussion and work style is the difference between a hobbyist and someone serious about their craft- in this game or any other.

Your right, keeping RH at 50% is precise and also basic knowlegde with most people nowadays, and its also impossible because not everyone has a dehuey or humidifier, so I just wanted to let him know it can fluctuate to a certain degree without much dismay.

Anybody can Google "indoor cannabis cultivation" and get all the precise info on growing just from reading, or watching a video on YouTube. Thats important, but its also important to let people know the basic limits that should not be crossed when it comes to environmental factors because if they do then it could be unhealthy for the plants.

 

[ttystikk]

Your right, keeping RH at 50% is precise and also basic knowlegde with most people nowadays, and its also impossible because not everyone has a dehuey or humidifier, so I just wanted to let him know it can fluctuate to a certain degree without much dismay.

Anybody can Google "indoor cannabis cultivation" and get all the precise info on growing just from reading, or watching a video on YouTube. Thats important, but its also important to let people know the basic limits that should not be crossed when it comes to environmental factors because if they do then it could be unhealthy for the plants.

If anyone reading this seriously thinks they can get 'all the precise info on growing just from reading or watching a video on youtube', then I will be happy to hear from them when they run into the inevitable problems... as long as they don't try to tell me I don't know what I'm doing because of what they read! LOL... shit...

 

[LexLuthor]

If anyone reading this seriously thinks they can get 'all the precise info on growing just from reading or watching a video on youtube', then I will be happy to hear from them when they run into the inevitable problems... as long as they don't try to tell me I don't know what I'm doing because of what they read! LOL... shit...

I never said you don't know what your doing, and yes, you can get "precise" info from reading and watching videos. I'm talking about all the basic grow info, not everything there is to know about growing. If you watch a video from Jorge Cervantes, for example, he precisely says what temps, RH, co2, ect. to keep your grow room at. Thats precise info, and I said that theres more to know then just the ideal, precise temps or RH. I was saying that instead of just telling people what the ideal environment is, but to also tell them the limits that they should not allow RH and temps to go above, or below. Before you said I was being imprecise and it leads to misunderstandings, well, if someone doesn't understand "keep the RH below 70%" then they shouldn't be growing.