CO2 bottle size?

[HigherTheHigh]

What size bottle would I need to feed two 4*3 tents?

The tents their going in are on permanent 12/12 and I would like to fill the tank ever 4 weeks so a smaller tank the better.

 

[Old Salt]

I figured someone would have answered by now. So here's my guesstimate, and how I arrived at it.

Do you have a CO2 monitor in the house? if so get that reading, if not use the atmospheric CO2 content of about 400 ppm. Next, what is the air flow FROM the tents? Take the CFM and multiply by 720 to get the volume of air moving through the tent in 12 hrs while it's light, or 1440 if you are going to inject it 24/7. Now all we need is the CO2 level you want in the tent. Above 3,000 ppm it starts to become dangerous for humans to breathe, and at 5,000 ppm it is considered lethal, so let's stick to 1500 PPM for our calculations.

CO2in = 400 PPM
CO2tent = 1500 PPM
CO2add = 1100 PPM

Let's assume for these calculations that your tents are 6' tall, and that you exchange the air once every three minutes.
Air Flow = (2 tents X 4 X 3 X 6) / 3 = 48 CFM (lets use 50CFM as it's a nice easy number to work with)
daily air = 720 * 50 = 36,000 cu ft (why spend the cash to inject CO2 during the dark hours?)

OK, now we need to compute how much CO2 we need per day.
CO2day = 36,000 X 1100/1,000,000 = 39.6 cu ft

A pound of liquid CO2 in a tank contains 8.741 cubic feet of gas, so you'll need 39.6 cu ft / 8.741 cu ft or about 4.5 lbs per day. I'd talk to the folks at a local grow shop to verify these figures. I haven't used CO2, so you may be able to use less. I'd also strongly suggest having a CO2 monitor in the room with your tents. I really don't want to read your obit.

 

[Hydroholic]

When I was growing in my producer I would average a 15lb bottle a month. That’s a little smaller space than you have. I would think a 5x5 tent would be good at a month per 20lb bottle.

 

[Hydroholic]

I bought my bottle and paid cash to fill.

 

[HigherTheHigh]

I figured someone would have answered by now. So here's my guesstimate, and how I arrived at it.

Do you have a CO2 monitor in the house? if so get that reading, if not use the atmospheric CO2 content of about 400 ppm. Next, what is the air flow FROM the tents? Take the CFM and multiply by 720 to get the volume of air moving through the tent in 12 hrs while it's light, or 1440 if you are going to inject it 24/7. Now all we need is the CO2 level you want in the tent. Above 3,000 ppm it starts to become dangerous for humans to breathe, and at 5,000 ppm it is considered lethal, so let's stick to 1500 PPM for our calculations.

CO2in = 400 PPM
CO2tent = 1500 PPM
CO2add = 1100 PPM

Let's assume for these calculations that your tents are 6' tall, and that you exchange the air once every three minutes.
Air Flow = (2 tents X 4 X 3 X 6) / 3 = 48 CFM (lets use 50CFM as it's a nice easy number to work with)
daily air = 720 * 50 = 36,000 cu ft (why spend the cash to inject CO2 during the dark hours?)

OK, now we need to compute how much CO2 we need per day.
CO2day = 36,000 X 1100/1,000,000 = 39.6 cu ft

A pound of liquid CO2 in a tank contains 8.741 cubic feet of gas, so you'll need 39.6 cu ft / 8.741 cu ft or about 4.5 lbs per day. I'd talk to the folks at a local grow shop to verify these figures. I haven't used CO2, so you may be able to use less. I'd also strongly suggest having a CO2 monitor in the room with your tents. I really don't want to read your obit.

Hey buddy, no i don't but I do plan on getting a meter for each tent in the next month, as for my airflow I run a 1500 cfm extractor on a adjuster at around 25% so around 350-400 cfm.

Yes I only plan to run the Co2 on lights on so 12h a day 7 days a week, I don't want to over do it with running the Co2 so what I plan to do I when we work out how much I need per tent then I plan to use 1 bottle with 1 regulator split between each tents but I'm only going to run 50-75% of the recommended Co2 levels just so it gives my plants that little extra help but not over the top.

When I was growing in my producer I would average a 15lb bottle a month. That’s a little smaller space than you have. I would think a 5x5 tent would be good at a month per 20lb bottle.

Help bud if that's about right then a 20lb bottle should do me a good 4-6 weeks then, thanks for that .

 

[Hydroholic]

Hey buddy, no i don't but I do plan on getting a meter for each tent in the next month, as for my airflow I run a 1500 cfm extractor on a adjuster at around 25% so around 350-400 cfm.

Yes I only plan to run the Co2 on lights on so 12h a day 7 days a week, I don't want to over do it with running the Co2 so what I plan to do I when we work out how much I need per tent then I plan to use 1 bottle with 1 regulator split between each tents but I'm only going to run 50-75% of the recommended Co2 levels just so it gives my plants that little extra help but not over the top.



Help bud if that's about right then a 20lb bottle should do me a good 4-6 weeks then, thanks for that .

Your extractor fans need to be shut off when you inject. If not it will pull everything out quickly. I run a controller that will kill the extractor fans when it injects then It lets it sit until the fans are absolutely needed.

 

[HigherTheHigh]

What controller is that @Hydroholic as I am looking to slowly upgrade to all high quality kit, also this is my first flowering run in my new tent so I would need to see what the smell is like when the fans go off.

 

[Hydroholic]

What controller is that @Hydroholic as I am looking to slowly upgrade to all high quality kit, also this is my first flowering run in my new tent so I would need to see what the smell is like when the fans go off.

I use the Iponics. It controls everything. I bought mine on eBay at a discount. When you start adding all the timers and everything I found this was a cheaper option. I like the data logging.

 

[TurboBucket]

Before co2 you need to make sure your enviro is on point. And that's not on point for an air cooled system. You need a sealed room to make efficient use of your bottled gas otherwise your just dumping money out the vent. In which case you can mail it to me and I'll tell you your plants look better every time I get a check. Lol

You may get lucky and increasing the temp to help the plants use the added co2 will reduce your need for ventilation. Temp range for co2 enrichment is 80-90°f you also need par levels over 900 at the canopy before there's enough energy available for the plants to even use the co2.

Sealed rooms need a recirculating scrubbing setup, depending on how tight your room is you may be able to go to multi pass scrubbing as opposed to single pass scrubbing that is typically used in grow tents.

More passes through the filter before the air leaks out removes more smell. Air that's vented to occupied spaces needs to be effectively scrubbed in a single pass so there is no odor. Multi pass doesn't have to be completely clean as it will be going through again before it leaks out.

Multi pass setups can use smaller fans and filters reducing the overall equipment and operating costs.

 

[Dutchman1990]

Hey @higherthehigh
So first thing as mentioned is make sure to get a CO2 monitor! It’s a critical investment when running CO2!

They recommend levels of 1200-1500PPM for high CO2 injections but you will see good results in the 900-1200ppm range as well. I would suggest a 20lb tank for your area if your planning to run a little lower than average for your CO2 levels and this should give you about a month each tank.

You need high PAR levels at your canopy as mentioned to really utilize CO2 and what it can potentially do for your garden!

Im sure you will get things figured out and I’ll be sure to tag along and see how you do!

 

[BooMtoLate]

Is it even worth pumping into a tent. I mean it's not really a sealed environment. I use the exhale bags but pretty sure its not doing anything. I don't have a means of doing a measurement though.

 

[Old Salt]

Is it even worth pumping into a tent. I mean it's not really a sealed environment. I use the exhale bags but pretty sure its not doing anything. I don't have a means of doing a measurement though.

The amount you need will depend on your airflow through the tent. If you read back posts you'll see that I computed a 20lb tank would last about 4-1/2 days with 50 CFM being extracted. It looks like Hydroholic and Dutchman have far less air being drawn out. They also may be using a lower concentration of CO2.

The other thing to take away from this, is that your environment MUST be well controlled to even make use of the added CO2. Light, temperature, humidity, and airflow all need to be within certain parameters to get the results that will make it worth while.

 

[HigherTheHigh]

Before co2 you need to make sure your enviro is on point. And that's not on point for an air cooled system. You need a sealed room to make efficient use of your bottled gas otherwise your just dumping money out the vent. In which case you can mail it to me and I'll tell you your plants look better every time I get a check. Lol

You may get lucky and increasing the temp to help the plants use the added co2 will reduce your need for ventilation. Temp range for co2 enrichment is 80-90°f you also need par levels over 900 at the canopy before there's enough energy available for the plants to even use the co2.

Sealed rooms need a recirculating scrubbing setup, depending on how tight your room is you may be able to go to multi pass scrubbing as opposed to single pass scrubbing that is typically used in grow tents.

More passes through the filter before the air leaks out removes more smell. Air that's vented to occupied spaces needs to be effectively scrubbed in a single pass so there is no odor. Multi pass doesn't have to be completely clean as it will be going through again before it leaks out.

Multi pass setups can use smaller fans and filters reducing the overall equipment and operating costs.

The environment their in now are great for normal airflow setup but yes I do see the problem with it not being air tight so I do see your point, my only outlay would be for the bottle and setup as I can get as many refills for free.

This tent however seems to be a lot more air tight in terms of smells compared to my past tents and the fan is hardly on.

So you can use Co2 with multi pass systems?

Hey @higherthehigh
So first thing as mentioned is make sure to get a CO2 monitor! It’s a critical investment when running CO2!

They recommend levels of 1200-1500PPM for high CO2 injections but you will see good results in the 900-1200ppm range as well. I would suggest a 20lb tank for your area if your planning to run a little lower than average for your CO2 levels and this should give you about a month each tank.

You need high PAR levels at your canopy as mentioned to really utilize CO2 and what it can potentially do for your garden!

Im sure you will get things figured out and I’ll be sure to tag along and see how you do!

Hey buddy yes I plan to get a great setup this year and then at least this way everything will last a lifetime hopefully.

Yes looking at the size of the bottle I think that's what I will go for, the idea is to be around 25-50% below guidelines, I'm not using the most powerful of lights as I'm using 2 Led SP 250's in one tent setup and two TSL 2000's in another tent, there each recommended for 2*4 grow spaces so each setup gets an extra 1*4ft of light so adding Co2 just makes me use that little extra light ect.

I read somewhere that those ranges of ppm would work but even ideally for me would even just be double what our ppm is now so I'm not asking a lot really.

Probably wouldn't see a result on my current setup as I'm already week 3 in flower.

Is it even worth pumping into a tent. I mean it's not really a sealed environment. I use the exhale bags but pretty sure its not doing anything. I don't have a means of doing a measurement though.

I used two of those in a 4*8 for a few runs and I can say when I got rid of them I noticed around 1-2oz drop in yield so they must work a little.

 

[BooMtoLate]

Ok good at least it doing something

 

[Hydroholic]

I don’t run C02 in this tent. I ran it with the MH lights because of the temps and it came with the system. The plan is to run a C02 burner (generator) and get away from the bottle when my house is completed. I hated having to go fill the bottle. It seemed to always to need filling when I was busy with other stuff.