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Totes ventilation holes, natural airflow, and humidity - Which direction is the flow really?
    #17962236 -

Heya!

I've been growing for quite some time, and for a while did so by making monotubs. I don't make monos anymore, but I still find various uses for the totes themselves, including fruiting chambers for other grow methods.
My question concerns the natural airflow that occurs within tubs (with mycelium inside) and how filters (poly-fil or tyvek) effect that flow.

I am NOT looking for advice on how tightly to pack my poly-fil, no problems there, ain't my first rodeo so to speak, and it's not for a mono.
I am NOT looking for recommendations from monotub growers, but instead those who know about the physics involved.

Please don't post an "answer" if what you have is an educated guess. I'd like this thread to contain true understanding and knowledge about this subject, for myself and those others that want a more thorough understanding of the flow.


:biggrin:

Using the tub for casing small containers of straight-grain means that much less air exchange is needed, so I'm working with the tub to have it hold best humidity while still getting more than enough air exchange.
My question concerns humidity, temperature, gas mixture, and air pressure.


I know that more humid air is less dense, thus it "rises" relative to less humid air.
Also, warm air rises above cooler air of course.


Thus, unless there's a factor I'm missing out on (which is why I post), it stands to reason that stuffing the top holes more tightly will retain the best humidity and several can be used instead for increased airflow.
However I often read where people do the opposite - keeping the bottom holes tight, but the top ones loose, even open in some instances.
Would this let that humid air flow more quickly out the top holes, causing the substrates/casing layer to lose increasing degrees of moisture to the new air?


Ultimately, my true question is: How does the humidity and warmth of the mycelium cause the air within the tub to flow, and how would reducing or eliminating airflow from the top Or bottom holes change this dynamic?
I read very differing statements about the natural air currents, and would like to know for sure how it works, to make the most of the FCs I have and to help in developing further ones.


Thanks! :heart:


--------------------
Intentionally or not, here in mushcult we are purveyors of love culture and enlightenment movement. Let's try to act like it!

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Edited by Violet (03/16/13 02:28 AM)

Extras: Filter Print Post Top
Re: About ventilation holes in totes, natural airflow, and humidity - How's the dynamic work? [Re: Violet]
    #17962365 -

Well, to put it simply, because.

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Re: About ventilation holes in totes, natural airflow, and humidity - How's the dynamic work? [Re: Violet]
    #17962381 -

Tyvek does not get used with monotubs.

We use it as a GE filter on jars because it restricts too mush airflow.

I have no other input that pertains to the main questions, I would like to know the physics behind it as well.


--------------------
                 
THIS HOBBY IS NOT FOR THE IMPATIENT! PLEASE BE PATIENT, DON'T BE A PATIENT!
A Tale of 10 Isolates, GT Cluster Clone Monotubs, RR's Let's Grow Mushrooms DVD,
SGFC(Shotgun Fruiting Chamber), Monotub Tek, Damion5050's Coir Tek, TL's Tek List, Frank's Tek List,
EvilMushroom666's Pasteurization Tek, How It Should & Shouldn't Look - NEW CULTIVATORS GUIDE
*** *** AFGHAN KUSH GROW LOG *** ***

Edited by PussyFart (03/15/13 11:13 PM)

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Re: About ventilation holes in totes, natural airflow, and humidity - How's the dynamic work? [Re: PussyFart]
    #17962456 -

Hi Violet! !
Heat rises so if your mono (or just 1 side of it) is warmer inside than outside there will be a natural exchange.  If the exchange is too great the mono will no longer be warmer and natural convection will cease.  This convection can be caused by warmth from lighting or thermogenesis.  Pinning and fruiting in cooler temps make dense fruitbodies. 

I have experimented with leaving the lids open 1/2-3/4" and then stacking NO DRILLING NO POLY. POLYFILL acts as a bacterial conduit after its wet. Its like a puddle. when the lids overhang its sort of like a gill.  you can fan a stack pretty easily all at once.

PS psuedo casing with crumpled wax paper is the shit.  nothing is gonna colonize that wax paper.


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Re: About ventilation holes in totes, natural airflow, and humidity - How's the dynamic work? [Re: PussyFart]
    #17962602 -

Indeed like I said in the post I know heat and humidity cause air to rise in the chamber. This leads me to suppose that upward current, as well as expansion of air in the uppermost of the tub, would gradually push the warmest and most humid air out the top holes and escort cooler outside air in the bottom holes.

However I read many statements about monotub airflow that suggests quite the opposite. Here are just a couple of those for examples...
Here Citric recently mentions "Fresh air in through the top, out through the bottom."

An older post, " Fresh air comes in through the top holes and pushes the heavier C02 out of the bottom holes. This is the basic philosophy behind a mono-tub and why it works."


Certainly there's no reason both can't be going on, and almost certainly they do to some degree even a small one. The air mixes somehow.

How would hot air be getting out if the cooler fresh air is coming in thru the top holes? Is it really freasible that the cool air coming in the top holes pushes the warm air with upwards motion out-of-the-way to get in, migrating out air in the bottom of the chamber? Would the cool air not fall down the sides and be what's pushed out a moment after, only mixing somewhat with the churning warmer air in the top-center area?


What makes more sense to me is that the warmer and humid air gradually migrates upwards and out the top holes, with fresh cooler and less-humid air being drawn in the bottom holes, then being humidified by the substrate and warmed by the mycelium.

But gotta know facts, and if I'm not considering any other factors.


Notahacker420 said:
Tyvek does not get used with monotubs.


(Not being iffy with you Notahacker, just being clear)
YOU don't use tyvek with monotubs. I've seen plenty of people, including "trusted cultivators", that have/do. Even the TCs disagree quite dividedly about those alternative filters if you do searches for posts about it.
Remember that there is postal tyvek and there is suit tyvek which have extremely different porous properties.
I've seen TCs use even postal tyvek over large holes before, and read once where FooMan said he liked suit tyvek more than poly, dunno if he kept that stance.


Also, remember, and I will reiterate:
I AM NOT MAKING MONOTUBS.
I am modifying old monotubs for a change in ideal properties as I am using them for a different method now, and getting a sense for inner-chamber air physics to best do so. Though surely coming to a nice answer about this can help mono users too.


--------------------
Intentionally or not, here in mushcult we are purveyors of love culture and enlightenment movement. Let's try to act like it!

PODS TEK - Growing Invitro with BRF/verm or Grass Seed containers
The simplest, quickest, safest tek!  For beginners, culturers, lazy people, stealth lovers, contam haters, and alternative seekers!
• Violet's Teks and Posts •

Extras: Filter Print Post Top
Re: About ventilation holes in totes, natural airflow, and humidity - How's the dynamic work? [Re: Violet]
    #17962726 -

Quote:
What makes more sense to me is that the warmer and humid air gradually migrates upwards and out the top holes, with fresh cooler and less-humid air being drawn in the bottom holes, then being humidified by the substrate and warmed by the mycelium.


That's sounds right. Currents like that are weak though and tyvek will significantly hinder it, try blowing through a sheet of tyvek to see for yourself. It also wouldn't make sense to have the holes larger/tighter on the top or bottom because for air to leave the chamber the same amount of air needs to be able come in to replace it.


--------------------

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Re: About ventilation holes in totes, natural airflow, and humidity - How's the dynamic work? [Re: Kizzle]
    #17962798 -

I have a theory that monos can succeed nicely when little or no air motion in the room is happening if tuned with varying light amounts of polyfil to promote this kind of natural cycle, but do better having holes stuffed thicker with polyfil and lots of airflow around them which generally exchanges/pushes air thru steadily all-over and with nice humidity retainance.
This has been my experience at least, and makes sense because that air disturbance would drive the exchange instead of steady rise from heat and humidity.

Kizzle said:
Quote:
What makes more sense to me is that the warmer and humid air gradually migrates upwards and out the top holes, with fresh cooler and less-humid air being drawn in the bottom holes, then being humidified by the substrate and warmed by the mycelium.


That's sounds right. Currents like that are weak though and tyvek will significantly hinder it, try blowing through a sheet of tyvek to see for yourself. It also wouldn't make sense to have the holes larger/tighter on the top or bottom because for air to leave the chamber the same amount of air needs to be able come in to replace it.


Yeah it sounds right to me too! But, it runs directly against what others have said on the matter, even calling the other premise "the basic philosophy behind monotubs and why they work"

Though, it seems they were thinking in terms of "heavier" CO2-laden air dropping out the bottom holes. This is probably not happening when there are other forces stirring air which wouldn't allow CO2 components to settle.

Exactly my thoughts in regards to stuffing holes. It wouldn't matter stuffing holes thicker on the top or bottom unless you have more holes on top or bottom, in which case we typically have more bottom holes, so indeed a bit more airflow in the top fewer holes would even it out some...

Tyvek was mentioned because of the variety of possible filters, however you should try blowing thru suit tyvek instead and see the difference :wink:


Here is why the solution would be relevant: If we confirm the consistent direction of airflow, as well as which filters lose humidity the least (will be easy to test), it will probably benefit moisture retainance to use that particular filter on the holes that air migrates out thru. If it happens to be a more air-restrictive filter, the polyfil of the other-level holes can be reduced to adjust. If the air flows up then more top holes can be used in the possible case of a more air-restrictive filter holding humidity better. Tho it's possible the air exchange to humidity loss ratio may not change from one filter to another.

For sure we'd know which holes are the inlets which is important because the humidity-retaining filters would be necessary on the outlets but not the inlets.


--------------------
Intentionally or not, here in mushcult we are purveyors of love culture and enlightenment movement. Let's try to act like it!

PODS TEK - Growing Invitro with BRF/verm or Grass Seed containers
The simplest, quickest, safest tek!  For beginners, culturers, lazy people, stealth lovers, contam haters, and alternative seekers!
• Violet's Teks and Posts •

Edited by Violet (03/16/13 02:08 AM)

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Re: About ventilation holes in totes, natural airflow, and humidity - How's the dynamic work? [Re: Violet]
    #17963302 -

Quote:
"An older post, " Fresh air comes in through the top holes and pushes the heavier C02 out of the bottom holes. This is the basic philosophy behind a mono-tub and why it works."


But what about the convection currents created by warm substrate. dont substrates generate heat? and the more substrate the more heat they generate? So surely a large monotub is going to create eough heat, that will create strong enough currentls to have an upward flow of air, that rises to the top and falls again.

So yes co2 is heavier that air, and can settle, but with the currents its going to stay mixed with the rest of the air.


--------------------

PF TEK - writeup by EvilMushroom666
Lets Grow Mushrooms - RogerRabbit & RoadKills website with sample videos plus the full PF TEK video series. Alot of great information - BUY THE DVD
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Re: About ventilation holes in totes, natural airflow, and humidity - How's the dynamic work? [Re: veda_sticks]
    #17963314 -

:whathesaid: Co2 will not settle to the bottom of a monotub, it will flow out of the holes with the heat currents.


--------------------
                 
THIS HOBBY IS NOT FOR THE IMPATIENT! PLEASE BE PATIENT, DON'T BE A PATIENT!
A Tale of 10 Isolates, GT Cluster Clone Monotubs, RR's Let's Grow Mushrooms DVD,
SGFC(Shotgun Fruiting Chamber), Monotub Tek, Damion5050's Coir Tek, TL's Tek List, Frank's Tek List,
EvilMushroom666's Pasteurization Tek, How It Should & Shouldn't Look - NEW CULTIVATORS GUIDE
*** *** AFGHAN KUSH GROW LOG *** ***

Extras: Filter Print Post Top
Re: About ventilation holes in totes, natural airflow, and humidity - How's the dynamic work? [Re: PussyFart]
    #17963428 -

I think people would get better answers if users had a form letter suggesting ALL the details they ought to share.

The details are important its like IDing a mush.

Instead of trying to foresee the future, just roll with it and be as observant as possible. 
Each tub is going to want something different unless they are all getting homogenized somehow.

Have a solution planned for each problem you acknowledge to be a threat.  Have the solutions available before the issue comes up.

Folks need to consider production scale and ambient conditions when giving advice to other growers.  Arid or winter advice is different then tropical or summer advice.

There are so many factors.  How deep is the sub (thermal mass).  how available are the nutes,  is it the tub on the top shelf or bottom shelf,  is the tub insulated by other tubs, how porus is the sub, did you noc ur mono heavily for fast expantion and more thermogenesis or did u try to stretch yr spawn out so the myc is jogging.  surface evaporation, wind chill, gravity, pressure, volume of the tub vs empty space........

Eliminate variables by following sci method

:heart:Thanks for sharing your Gandoli pom grow by the way...

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Re: About ventilation holes in totes, natural airflow, and humidity - How's the dynamic work? [Re: aris]
    #17963517 -

:nothingtoadd:


--------------------

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Re: About ventilation holes in totes, natural airflow, and humidity - How's the dynamic work? [Re: thundahoof] * 1
    #17963606 -

Quote:
An older post, " Fresh air comes in through the top holes and pushes the heavier C02 out of the bottom holes. This is the basic philosophy behind a mono-tub and why it works."




The lack of physics understanding by members here is underwhelming at times.  CO2 mixes with the air as science has known for centuries.  It does not settle to the bottom of a ventilated tub, nor does it get 'pushed out' bottom holes. :lol:

CO2 mixes with the air and goes where the air does.  In my mushroom farm, the CO2 level is 200 ppm higher near the ceilings than near the floor.  Why?  Because of convection and the fact that warm and humid air rises.  When the CO2 mixes with this warm and humid air, it rises too. 

Substrates create heat.  Lighting creates heat.  These factors cause convection in the tub.  Nobody can map exactly what the currents are doing because they'll constantly change based on ambient weather conditions of humidity and atmospheric pressure, as well as whether your light is on or off, etc.
RR


--------------------
Download Let's Grow Mushrooms



semper in excretia sumus solim profundum variat

"I've never had a failed experiment.  I've only discovered 10,000 methods which do not work."
Thomas Edison

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Re: About ventilation holes in totes, natural airflow, and humidity - How's the dynamic work? [Re: RogerRabbit]
    #17963881 -

This is making plenty of sense to me!


So. Although it can depend on filtering, ambient temperature and airflow, and the layout of holes, it seems we can typically expect the physics of warm humid air inside the tub to flow "up&out" and cooler fresh air in thru the bottom holes.
That is the opposite of almost every statement I've read on here about monotub air flow.

Fans throw-off that dynamic, and replace the natural air current with the force of air pressure and disturbance around the tub.

Further, surely poly-fil must change it lots depending on how used.

I suspect Tightly-packed polyfil on ONE of the levels will "regulate" the flow of air indeed, as is often thought, but actually by re-directing the current not slowing it per se.
As in, leaving top holes open causes exchange amongst the top area of the tub, but less air is going thru the bottom holes, meaning air is going in -and- out the top holes, a horizontal current in the top area more than a vertical current throughout the tub's air.
Having top holes stuffed and bottom ones open would do the same thing in the lower area, especially since there are typically more bottom holes.


I see where lots of cultivators use "top holes open" or something of the like. Where this would indeed increase airflow, seems to me like having 2 or more open top holes would rather cause air to exchange between those holes instead of speeding-up the tub's natural current.

If the most-humid air is in the top, then allowing the top air to exchange more freely will continually draw moisture from the substrate/casinglayers below, though letting out the heat buildup.
However, having the bottom air exchange a bit freely would better-retain the humidity above and increase airflow thru the many more holes below, though this could just as easily draw moisture off the subs.

Thus what seems to be becoming the most important in my mind is encouraging & retaining a down-to-up flow (when not counting on fans for pushing FAE), in which case having ANY of the holes stuffed so tightly will choke or halt that particular motion. But if this is done correctly the humid air will be going out the top, so having moisture-retaining filters on the top holes will hold humidity better while still allowing for the most air exchange.



Starting to think that an experiment with "inverted" approach to the holes might be in order, again unless there's something I'm missing.
I'll likely experiment making a mono (yeah yeah I don't make monos, but I gotta know) with 6 medium-small holes at substrate level lightly stuffed, and 6 or more medium-large ones in top stuffed a bit more tightly or with an alternative filter.


--------------------
Intentionally or not, here in mushcult we are purveyors of love culture and enlightenment movement. Let's try to act like it!

PODS TEK - Growing Invitro with BRF/verm or Grass Seed containers
The simplest, quickest, safest tek!  For beginners, culturers, lazy people, stealth lovers, contam haters, and alternative seekers!
• Violet's Teks and Posts •

Edited by Violet (03/16/13 12:31 PM)

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Re: About ventilation holes in totes, natural airflow, and humidity - How's the dynamic work? [Re: Violet]
    #17964520 -

Just something to keep in mind in designing a FC that doesn't get mentioned a lot... Mold spores travel along with the moving air. By having air currents moving near the substrate it will help prevent those spores from settling onto it. Pockets of still air is where mold tends to grow.


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Re: About ventilation holes in totes, natural airflow, and humidity - How's the dynamic work? [Re: Kizzle]
    #24369424 -

Which is better setup for each design? This is the first time growing for both myself and the misses and she refuses to do it my way, my way is using a air pump so that never is fanning needed, her way is fanning. I will be using holes with poly fill for the old air and co2. Her way is stubborn, she doesn't think holes is a good thing, she just wants to fan and she thinks that will work better than having any holes at all.

My question is this, which hole design is better? Either the ""legendary shotgun"" with holes every 2 inches or the big (but fewer) hole design as seen here
for specifically what I am doing with my FC?

Thank you so much for putting this confusion to rest for newbies like myself and others.
Which FC is better? The 4-8 big hole or shotgun with small holes?
You may choose 1


Votes accepted from 06/02/17 12:38 AM until the end of time
You must vote before you can view the results of this poll


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