Is this math correct??

My room mate and I got nice and baked and were trying figure out how long our CO2 tank/regulator had to be flowing to raise the grow room CO2 ppm to ~1500… And this is what we came up with.. is this method realistic?
(some measurements are in metric, others imperial, sorry, the conversions are pretty easy.. I just don’t wanna do more math)

‘normal’ CO2 levels in the atmosphere are around 300-400ppm.. so the concentration of CO2 in the atmosphere is around 0.03% (for arguments sake)

The grow room (which is 1.944m3) is situated in the storage room which is 12.5m3…. so there is approximately 12.5m3x0.0003=0.00375 m3 of CO2 in the storage/grow room.

To achieve 1500ppm or 0.15% CO2 concentration, we needed 0.01875m3 of carbon dioxide… ( 12.5x0.0015=0.01875 )

So we have a difference of 0.01875 – 0.00375 = 0.015 m3 of carbon dioxide

We roughly measured the flow rate of the carbon dioxide tank (PSI was about 2.5) by timing how long a large balloon took to fill a 1gallon with CO2.. it was something like 54 seconds.. by doing some converting, we solved our flow rate to be 0.004205m3/minute

One last calculation… 0.015 m3(amount needed) / 0.004205m3/minute (rate) = 3.57.. or 3 minutes and 34 seconds

So that tells me that it takes 3mins, 34secs to raise the CO2 ppm to 1500…. And now my question, is this a realistic method of tackling this problem??

Answers are below

chromer said:

My room mate and I got nice and baked and were trying figure out how long our CO2 tank/regulator had to be flowing to raise the grow room CO2 ppm to ~1500… And this is what we came up with.. is this method realistic?
(some measurements are in metric, others imperial, sorry, the conversions are pretty easy.. I just don’t wanna do more math)
If you want us to read this and do the math to figure out what you are talking about, your crazy. Its not going to happen, I am not in the mood to get the pencil and paper out and check it, its not THAT interesting.


So that tells me that it takes 3mins, 34secs to raise the CO2 ppm to 1500…. And now my question, is this a realistic method of tackling this problem??
I dont know man, you did all the math, you tell us.

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looks ok to me.
its close enough to know you can turn the tap on for 3.5mins and be near enough to the right levels.
now calc how much and how often to add more co2 to maintain 1500ppm.

paddy510 said:

looks ok to me.
its close enough to know you can turn the tap on for 3.5mins and be near enough to the right levels.
now calc how much and how often to add more co2 to maintain 1500ppm.

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That is the magic question! How much CO2 will your plant use during heavy growth? The only way to properly use a tank is with a PPM sensor and a solenoid. These are so fool proof that even fools like me can use them!

WillieNelson said:

That is the magic question! How much CO2 will your plant use during heavy growth? The only way to properly use a tank is with a PPM sensor and a solenoid. These are so fool proof that even fools like me can use them!

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I am interested in your set up. Sounds like the right idea for me if any dummy can use it, I fit that category. VV

chromer said:

…. And now my question, is this a realistic method of tackling this problem??

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This is the quetion in the thread... i know the math is right... if your going to comment, please read it first

Right now i've been turning the gas on 4x a day hoping it will help but i'll look around some more and see what other ways i can regulate this, without buying a ppm monitor

VictorVIcious said:

I am interested in your set up. Sounds like the right idea for me if any dummy can use it, I fit that category. VV

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Victor, the only way to get efficient control of CO2 from a tank is unfortunatley a little complex to explain. I use a Telaire 24VAC sensor(called a humidstat or ventistat or humidivent or something similiar) that provides a 24VAC relay that closes whenever the CO2 level drops below 1700 PPM. That relay then closes a 24VAC contactor with 120VAC on the contacts which opens a solenoid valve on the CO2 tank, and lets the CO2 out into the room. When the CO2 comes up to 1700 PPM the relay opens, the contactor opens, and the solenoid on the CO2 closes. I use 1700 PPM b/c the location of the sensor is not quite far enough from the hose that brings the CO2 in from the tank. By my estimate the entire room is always kept at least 1500 PPM wether or not I am there. The only thing I do is change tanks. The tanks are kept in my garage for easy changing and exchanging off of my truck.

I use the another identical contoller in a similar fashion to control the CO2 generator in the basement of the house. PM me if you have any specific questions. ~ WillieN

WillieNelson said:

That is the magic question! How much CO2 will your plant use during heavy growth? The only way to properly use a tank is with a PPM sensor and a solenoid. These are so fool proof that even fools like me can use them!

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i know normal timer solenoid systems are around $100-$150, so how much more do these cost?
any ideas of a cheap place to order them for?

I built my system with a PPM sensor, contactor a,d a solenoid. Total cost new retail, 300-500 depending on how hard you look. Today using ebay parts I could make it work for $169 shipped, I have wire and other jargon on hand...

When will you people learn, weed and math don't mix! This is how the wall-mounted talking fish was invented. DO YOU WANT TO BE RESPONSIBLE FOR THAT?! No, I didn't think so.

for some of us olf fogies...maybe you can increase the font size so that we don't have to sit on top of our monitor to read that print!.....j/k....seems to make sense to me...but then I'm just an old fogie, and don't even know how to use a calculator....