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Bugzy
Magician



Registered: 03/18/09
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Pressure
#11735364 - 12/29/09 01:27 AM (15 years, 22 days ago) |
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I am trying too understand how air circulates(FAE) and how GE escapes tubs without anything other than tyveck/poly, espeacially poly.There seems like a lot of restriction.
Is there some form of pressure present? I have heard of negative/positive pressure b4, but if so, how do you maintain or even achieve this "pressure"?
Im thinking air flow. how does air circulate enough too exchange gas/air? It seems too me that monos are just still air boxes until you fan them. Hell, just sitting here with a small fan doesnt even make the slightest breeze... IDK, direction out of this confusion is what I need.
-------------------- American by Nature.... unamerican by Law
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Fahkface
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Re: Pressure [Re: Bugzy]
#11735406 - 12/29/09 01:42 AM (15 years, 22 days ago) |
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When mushrooms grow C02 is produced. C02 is heavier than oxygen and sinks down. Since there's not going to a vacuum in the tub, oxygen needs to refill the "empty" space, the C02 left behind.
This way, fresh air is getting in, while the heavier C02 is pressed out of the holes that are further down.
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Bugzy
Magician



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Quote:
Fahkface said: When mushrooms grow C02 is produced. C02 is heavier than oxygen and sinks down. Since there's not going to a vacuum in the tub, oxygen needs to refill the "empty" space, the C02 left behind.
This way, fresh air is getting in, while the heavier C02 is pressed out of the holes that are further down.
Your saying that when co2 builds up and has nowhere too go, the pressure of the gass forces it through all the places it can, therefore creating a vacuum in the tub, pulling fresh air in through the tyveck/poly.
Basically, it natuarlly recycles the air when need be.
How can you test a tub for ge/fae too make sure its not too restrictive or unrestrictive?
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SillyBilly
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Re: Pressure [Re: Bugzy]
#11735560 - 12/29/09 02:31 AM (15 years, 22 days ago) |
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I was just at a hydroponics store the other day discussing co2 monitoring equipment because I have mentioned I wanted to know if there was a way to know the amount of co2 build up in the top of my gh. He said that they are very expensive.
And I just googled for them because you reminded me as well as looked on ebay. So they range from around 70 to like 500$ I think its my next buy since I just bought a digital ph meter which was a good investment.
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Fahkface
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Re: Pressure [Re: Bugzy]
#11735571 - 12/29/09 02:33 AM (15 years, 22 days ago) |
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By growing mushrooms in there...
Seriously, the effects of a too high C02 content are pretty easy to see. Long stems with comparably small caps are a sign for a too high C02 content.
I, myself haven't any experience with monotubs, so I never really dealt with this issue. But it's more or less the same with regular FC's. The concept is the same.
As long as you go with the regularly suggested ways to make a tub, you should be fine.
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Fahkface
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You sure could measure your C02 content by using a C02 monitoring device, but as SillyBilly already said, they're pretty expensive.
I doubt, that there are bigger differences in this way, as long as the tub is about as big, as the ones people used, who made tutorials on this.
So you probably just have to do it the way people with experience do it
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Bugzy
Magician



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Just trying too understand the process of exchange, more or less paint a picture of this process in action in my mind
-------------------- American by Nature.... unamerican by Law
"Out of all the things I've lost, I miss my mind the most."
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Fahkface
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Re: Pressure [Re: Bugzy]
#11735653 - 12/29/09 02:50 AM (15 years, 22 days ago) |
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You already got it!
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Bugzy
Magician



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I was talking about testing the tub itself without sub in it. I was asking if there was a way to test the airflow/ge qualities of the tub before using it.
This way you can tweak the amout/size of holes or thick/thin poly.
I got the pressure part figured out, Thanks
-------------------- American by Nature.... unamerican by Law
"Out of all the things I've lost, I miss my mind the most."
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SillyBilly
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Re: Pressure [Re: Bugzy]
#11735767 - 12/29/09 03:37 AM (15 years, 22 days ago) |
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Well you could take note of highly productive spore counts in some grows. If you look at grows where there is a lot of spores you will notice they go everywhere. Even in what seems to be still air.
-------------------- By the livin' Gawd that made you,
You're a better man than I am, Gunga Din
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Fahkface
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Re: Pressure [Re: Bugzy]
#11735777 - 12/29/09 03:39 AM (15 years, 22 days ago) |
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I see, OK.
However, you need an indicator for checking on the airflow. And we suggested two to you. Mushrooms and a co2 monitoring device.
For checking how well it works, without eventually fucking up a whole grow (though you could easily adjust your setting if needed), you could go with a single BRF cake and see how well it goes. If they grow well, you should be fine.
Sorry, nothing else appears to me
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Bugzy
Magician



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Ok I see where everyones coming from, the co2 thing threw me of track. Thanks for the info.
-------------------- American by Nature.... unamerican by Law
"Out of all the things I've lost, I miss my mind the most."
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veda_sticks
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Re: Pressure [Re: Bugzy]
#11735967 - 12/29/09 06:15 AM (15 years, 22 days ago) |
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co2 doesnt all just sink to the bottom of a fruiting chamber. thats not the reason for having holes in a monotub type fruiting chamber at the substrate level. You also have holes at the top as well. Having holes at substrate level allows fresh air to come in at the surface of the substrate where its needed.co2 is heavier than o2 but not by much and with the small air currents created by heat its going to stay somehwat mixed with the rest of the air.
Tyvek doesnt allow fresh air exchange only gas exchange. Polyfill is slightly better but still really doesnt provide proper fae and thats why alot of people will use a fan circulating air around the room the monotub is in.
Dont forget that your substrate produces heat, and in a tub that will create small currents of air travelling up.
Ive never used polyfill in a monotub type setup, 1/4 inch holes work great, unrestricted FAE while still maintain proper humidity. I also would manually fan a few times a day.
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Fahkface
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That it doesn't work only one way, should be as clear, as oxygen and C02 mix up, because of "gas" movement in the tub
But since C02 is heavier, it's more likely for it to exit through the lower holes in the tub, than through the upper holes, even is some of it is mixed with oxygen.
Since when doesn't tyvek allow FAE but only GE? Tyvek is used as a filter for substrate jars, which require FAE and GE, so it should work!?! (no pissy, but a serious question ).
Anyway it's not even suggested anymore. Smaller holes will do the same job as polyfil or tyvek, since it's not about contams or anything, but about the reduction of "wind", so the tub doesn't dry out.
Edited by Fahkface (12/29/09 07:00 AM)
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Doc_T
Random Dude




Registered: 03/06/09
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Loc: Colorado
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Quote:
But since C02 is heavier, it's more likely for it to exit through the lower holes in the tub,
Theoretically, maybe. But in actual practice, no. The air stays mixed. If CO2 settled out like that, you couldn't sleep on the floor.
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Bugzy
Magician



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Quote:
veda_sticks said: co2 doesnt all just sink to the bottom of a fruiting chamber. thats not the reason for having holes in a monotub type fruiting chamber at the substrate level. You also have holes at the top as well. Having holes at substrate level allows fresh air to come in at the surface of the substrate where its needed.co2 is heavier than o2 but not by much and with the small air currents created by heat its going to stay somehwat mixed with the rest of the air.
Tyvek doesnt allow fresh air exchange only gas exchange. Polyfill is slightly better but still really doesnt provide proper fae and thats why alot of people will use a fan circulating air around the room the monotub is in.
Dont forget that your substrate produces heat, and in a tub that will create small currents of air travelling up.
Ive never used polyfill in a monotub type setup, 1/4 inch holes work great, unrestricted FAE while still maintain proper humidity. I also would manually fan a few times a day.
Thats interesting, I havn't heard of using 1/4" holes in a mono before. Could you elaborate on your tub? Such as amount of holes, placment, etc.
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cowfodder
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Re: Pressure [Re: Bugzy]
#11736401 - 12/29/09 09:53 AM (15 years, 22 days ago) |
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Quote:
Bugzy said:
Quote:
veda_sticks said: co2 doesnt all just sink to the bottom of a fruiting chamber. thats not the reason for having holes in a monotub type fruiting chamber at the substrate level. You also have holes at the top as well. Having holes at substrate level allows fresh air to come in at the surface of the substrate where its needed.co2 is heavier than o2 but not by much and with the small air currents created by heat its going to stay somehwat mixed with the rest of the air.
Tyvek doesnt allow fresh air exchange only gas exchange. Polyfill is slightly better but still really doesnt provide proper fae and thats why alot of people will use a fan circulating air around the room the monotub is in.
Dont forget that your substrate produces heat, and in a tub that will create small currents of air travelling up.
Ive never used polyfill in a monotub type setup, 1/4 inch holes work great, unrestricted FAE while still maintain proper humidity. I also would manually fan a few times a day.
Thats interesting, I havn't heard of using 1/4" holes in a mono before. Could you elaborate on your tub? Such as amount of holes, placment, etc.
Basically a hybrid mono/sg. Post right above yours, click on Doc_T's mini monotub link.
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Bugzy
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Thats what I was thinkin, but I was curious to see Vedas tub and see if he used the same sg style holes or did somthing a bit different with the hole arrangement.
Good Idea:thumbsup:
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RogerRabbit
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The lid on a rubbermaid tub lid doesn't fit tight. There's a gap all the way around the edge, thus you're getting a small, but constant air exchange. Second, CO2 doesn't stratify in the bottom as many think. It's only slightly heavier than air, and mixes readily with it. The CO2 level at the bottom of my mini-greenhouse is no higher than at the top, and often it's actually higher at the top if the lights are on.
You have to remember that the substrate produces heat, and this causes turbulence. Nature also hates an imbalance. If the CO2 level inside your greenhouse is higher(or lower) than outside, the air/gasses will naturally exchange to balance out.
Gasses will exchange through tyvek and polyfill, etc. Air will not. If you doubt this, try to blow through a piece of tyvek and see if you can feel the wind on the other side.
I purchased a fairly inexpensive CO2 monitor that actually works. It has a set of contacts that can be used to operate an exhaust fan based on the CO2 setpoint. RR
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Fahkface
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Re: Pressure [Re: Doc_T]
#11736503 - 12/29/09 10:22 AM (15 years, 22 days ago) |
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It is indeed theoretical, but only to a certain degree. When it comes to the C02 content in the air, this is -at the moment- at about 0,04%. So far from lethal. The fact that there's no global concentration of C02 near the ground (but only at certain places) is caused by several factors. Things that are described by "Dalton's law" and the build up of atmospheric inversion and conversion etc.
However, if you have a steady temperature in your monotub, caused by a heating device, these processes don't happen as much as they do, when the monotub isn't heated and the temperature varies because the room temperature varies as well, due to night and day differences in temperature etc.
And...Well... I see, that I go out on a limb on that one, so I better stop
In the end, holes are required to provide the required FAE and simultaneously GE
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