CO2 from dry ice=plausible?

[Slezman]

Whatup everyone,

My friend has finally convinced me to start growing with CO2 (I did put up quite a battle though).

I work in a rather large laboratory and have a regular easy access to dry ice. I can get as much as I can carry as often as I want. Since I'm cheap and I want to save as much $ as possible, I was thinking of using it as my source for CO2 (for all those who don't know, dry ice is CO2 in it's solid state).

If I were to use it, I would just probably put it in the middle of my growroom so that it could sink through the leaves to the bottom and so it wouldn't get wisked away by my vents at the top. Hopefully it would reduce temps too (sublimination is an endothermic process, therefore producing "cold").

I was just wondering if anyone has heard of this method for CO2. Do you all think it's plausible? How much CO2 do you think I would need on a daily basis ( I guess I could just monitor ppm and adjust but it would be easier to know exact amounts)?

-Slez

 

[JollyGreenGiant]

I had this very same thought the other day. I think it seems totally plausible and minimally help cool the room for a short time.

 

[R4st4]

Dry ice is CO2 which has been cooled yo -109 degrees, at which temperature it becomes a solid. it cost aboute yhe same as the gas in tanks. It usually comes in 30 pound blocks which evaporate at the rate of 7 % a day when kept in a freezerAt room temperature, the gas evaporate considerablt faster,probably ssuplying much more than is needed by the plants.

yes just have it in the middle of the room, a freind of mine dose it he use 1-2 pounds each day.

 

[Snowdog27]

This question has been asked many times on this board just do a search on dry ice, most times its not worth the money and hassle but if you can get it for free then why not. You will have to put it above your plants so the co2 will sink down through the top's of your plants and make sure your fans are off other wise you will just be wasting your time.

 

[BlindDate]

First, it has been my life long goal to dispel the "sinking" CO2 myth.

CO2 does NOT sink! It disperses and mixes in the air. You can put it above your plants, below your plants or anywhere in the room. Just like you don't come home from vacation to find that the air in your house has separated into layers of Oxygen, Nitrogen and CO2. That would be absured, correct? It's called dispersion of gasses.

Now to answer your question:

Dry ice will not work, since it evaporates WAY too fast and you cannot run CO2 in an unsealed room.

The only way you can get it to work would be to seal the room and then throw a small CO2 icecube in every hour. Good Luck!!

 

[Maj.PotHead]

yes dry ice can be used as a source of co2 can be kinda costly depending on grow erea size n all http://www.icmag.com/ic/showthread.php?t=29757&highlight=dry+ice+co2 some reading on the very subject there's a link by Verite Carbon Dioxide Enrichment Methods very interesting

 

[Guest]

BlindDate you have a good point about gasses mixing If I remember correctly I think its called the Brownian theory or some such shit.Thats a true point but there's one thing to consider,being that its heavier than air there will be a greater concentration down low.Its like if you could see co2 and it was black and the air was clear the bottom of the room would be a darker shade of gray than the upper part if that makes sense.I have used a co2 propane generaot for years and in the instructions and on the advice of the hydro store guys,I use small oscillating fans pointing upwards through the plants in order to circulate the heavier co2 through the plants more effeciently.If you do a google chack on using fans with co2 you will see for yourself

 

[BlindDate]

Skeletor,

Hydro store guys and the people who make those propane CO2 generators are equally cluless. Yes, good air circulation is helpfull inside any grow room for temperature and leaf aspiration etc., but it has nothing to do with "heavy" CO2.
There WILL NOT be a greater concentration down low. The only greater concentration will obviously be near the source untill it mixes, or if using a burner at the ceiling since the air is hot until it cools. regardless of where the source is. Up, down, does not matter. If that were the case, the first mile of the Earths surface would be CO2 and we would all die.

But don't take my word for it, Use your meter and do a test. Shoot a blast of CO2 into a still room. Wait a few hours and then take a reading at the ceiling and at the floor. Testing for yourself is the best way to learn. Then go out and help me end this moronic urban myth.

 

[Guest]

Blind date I dont explain things too well sometimes but do this go on google and put in co2 heavier than air just like that and look and the first thread on the first page,co2 properties.They talk about how it "pours like water" through the air because its heavier.Your point is taken too but it really is beneficial to use fans pointing upward through the plants I googled that one up too long ago when I first bought the generator

 

[KillerDemo]

how about using c02 tablets?

 

[RM - aquagrower]

Slezman,
since you can get it for free, i say why not use it. just get a small cooler a little larger than the blocks you have access to. drill a small hole thru the top and bottom of the cooler, and suspend it above a circulation fan, with the block of dry ice in the cooler of course.

what will end up happening is that as the block evaporates, the CO2 will trickle thru the bottom hole and be blown into the canopy, not because the CO2 is "heavier than air", but because it's colder, and colder air sinks.

 

[iamhigh]

Blind Date lets not get too ignorant. Im sure those guys that make Co2 generators have a general idea of how the gas works. I think the "sinking" co2 only applies to Co2 supplied from a Ice block. Being that he co2 is sill nearly freezing its going to drop. When you throw a block into water the vapor doesnt rise straight up, it will stay down in the bowl and seep over the edges. Granted it will come to room temps it still drops before it reaches room temps.

 

[Slezman]

Sorry I haven't responded to anybody's posts yet. . . I was busy all day getting my cab setup. It's starting to look very pretty, can't wait to get my girls in there.

Ok, so the consensus seems to be yes, dry ice can be used for enhancing CO2 levels.

Blind date: CO2 definitely sinks. . . Put it in a cup and add some water and you will see the gas poor over the rim of the cup down to the floor. It's not because the density of the CO2 is different, it's because the air is colder.

However, I am worried that with my ventillation (275 cfm dayton), it won't actually be that effective cause all the air is being sucked to the top of the cab . I'm thinking of using the cooler method mentioned above and just running little air lines to the base of each girl and putting that gas right up her skirt.

I'll be posting pics when I get everything just the way I want it.

(sorry to ask this question when there was already info available. I guess I just thought I had a novel idea. ha)

 

[BlindDate]

Yes of course cold air or CO2 sinks. Who said that it did'nt?

 

[Guest]

You did stoner in your first response,co2 does NOT sink is exactly what you said lol

 

[foaf]

even bought, dry ice costs about the same as bottled co2 around here, a dollar a pound.

controlling the amount will be hard, especially turning off the co2 at "night". id buy a meter, but that would ruin the whole "cheap" deal.

put you dry ice in a thick styrofoam ice chest, cut 2 little holes in it and put a little computer fan in one of the holes. instead of having your meter turn on the solenoid to a tank, have it turn on the little computer fan to blow some co2 out of the chest. ive thought about it, and thats about the best I could come up with. without a meter, you will be very very unlikely to be in the desired range, most likely you will go way too high if you dont have ventilation, and of course you will go to ambient real quick with ventilation.

in the absence of any air flow or circulation, the co2 will concentrate along the floor to a great degree, now of course it will, as pointed out, eventually mix even without a fan or flow, but it will concentrate low in the room, especially since it is cold at first. gasses are totally miscible with each other so once they mix, they will never ever settle out again, its not like oil and water.

 

[ChaoticEntity]

just get your vents in order,

100,000ppm of CO2 will kill you, sounds like a lot but if you've got 5lbs melting in a sealed room you'll hit pretty damn close to 100k ppm. at 50k ppm you'll feel signs of intoxication(your brain isn't getting enough O2) at 100k you'll pass out and asphyxiate(die)

Plants will suffocate as well, so if you are going to use dry ice you need to do a couple of things, first you need to see your daily evaporation rate across a low and high temprature, then you need to figure out the relative PPM that said evaporation creates, otherwise you stand to do your plants more harm then good.

Also keep in mind that as much as the leaves like CO2, the roots do not, broad concentration of CO2 in the roots limit the plants ability to grow, frankly the best(for the plant) way to introduce CO2 is to use bottled gas or other means that allows flow at a constant rate as well as venting your exhuast to the outside.

It is possible to use dry ice, I would get a nice cooler and put it in there with a hole drilled in a cooler and plumbed into the flowering area, with the caveat that the room temprature doesn't vary much and you know how many PPM of CO2 you're putting into the air.



BTW, CO2 does indeed sink, it's just that small movement will allow the air/CO2/N2/whatever to mix with great ease. O2 and N2 don't normally seperate due to their similar density

 

[Guest]

what are other ways of getting CO2 into your room. besides the proppane CO2 generators. ???i have heard of the CO2 tablets do they work and where do you get them??what else works??could i just take a lil canaster of c02 for a airsoft and crack that?

 

[MTF-Sandman]

There's lots of sources of CO2...but most of them won't provide enough CO2 at a controlled rate. Dumping off a 1oz CO2 cannister won't do anything for the plants since they need a steady supply of elevated CO2 levels to take advantage of it.

Tanks of CO2 and burners are pretty much the only reliable ways to get your levels up. Sugar/yeast, baking soda/vinegar drips and other ways will work, but they are a huge PITA to maintain and are not readily controllable....not too mention probably more expensive in the long run.

 

[Guest]

^^^ unless you brew your own beer next to your grow, that way you get beer and weed... and a good excuse for co2 tanks and other items