Have you ever though about adding CO2 in a vented grow room? Chances are if you did any research at all you were told co2 is only for sealed rooms. Well that’s just not true! If you are in a grow tent or closet it is absolutely possible. So read on and I will tell you how to add co2 to a vented grow.
The Truth About Adding CO2
Now I am not going to tell you the science behind how CO2 works on a biological level because there is a ton of shit about that online. But I am going to tell you how to run co2 in a vented grow room.
First you need to know co2 is not some magic elixir. You should only think about running co2 in a dialed in grow environment. It cant cure sick or crappy strains, over or under watered or fertilized plants and weak lighting. But if everything is running as it should it can bring you to the next level.
Secondly it is going to cost you some money to get started. Once you have the equipment it is pretty cheap to run co2. Don’t waste money on bags full of compost or mushrooms or whatever they fill them with. They dont work that well and cost more than refilling a CO2 tank.
What To Expect From CO2 Enrichment
In a properly set up grow tent or closet you can expect a 25% increase in yield along with bigger, frostier and harder buds.
Say you grow 4 crops a year, which is not hard, especially with a separate veg space. Because of the increased 25% yield from growing with co2 you will actually end up with 5 crops! That’s right! ADDING CO2 IS A NO BRAINER BECAUSE YOU GET AN EXTRA GROWS WORTH OF WEED FOR ONLY THE COST OF THE CO2.
Yield increases are great but it’s even better when you can also expect better quality weed too. Buds will be harder,larger and have more trichomes.
But like I said before most people say using CO2 in a vented grow is a waste of money. Well if you run your fans constantly that might be true. But it only cost about $20 to fill a tank and a tank or 2 will probably get you through a grow and then some.
A lot depends on the size or your grow space and how tight it is. It does not need to be air tight but a tent or room wrapped withshould work fine.
My closet is 32 inches wide and 6 feet long. To make things easy I will assume it is 3′. Using 3′ x 6′ by 8′ I come up with 144 cubic feet I need to fill (L x W x H = Cu. Ft.). There are charts that you can use to estimate CO2 usage based on your footage. More on that later. My figures show at 1200 ppm a tank should last about a month but I wont know for sure for a while yet.
So who cares if some gets vented or leaks out as long as we are getting the results we want? Personally I would spend $20 a week for a 25% yield increase wouldn’t you? Think of all the shit we waste money on and get no return from.
How To Add CO2 To Your Grow Tent Or Closet
I shot a video the day after I added co2 to my grow closet and wanted to share it here. It doesn’t cover everything. But dont worry because I will go into more detail later. It does give you a good idea of how this works though.
You can also follow my grow at https://420grower.org/gelato-33-takes-over-the-grow/ That way you will be able to see my co2 grow room setup at work and decide for yourself if co2 supplementation is worth it for your grow closet or tent.
Supplemental CO2 Enrichment Day 7
I have been running CO2 for a week now. It is hard to tell a difference in the plants themselves at this point. What I can see is an increased metabolism which obviously means healthier and happier plants. They are using 5 gallons of water every 2 days and eating over 200 ppm during this time. I would say this is close to double the rate I was seeing before.
Overall adding CO2 has been successful. So far temperatures have not really been an issue. LEDs need to be run warmer than HPS by at least 5 degrees. They do not put out any infrared so the higher temps compensate for this. Leaf surface temperature or LST is the only accurate way to measure grow room temperature so buy yourself a $20 temperature gun if you dont already have one.
Here’s What You Need To Add CO2 To Your Grow
20# CO2 Tank
At the very minimum you will need a tank and a regulator. I recommend using a 20# co2 tank for a closet or tent. They weigh about 50# full which most people can handle without much difficulty. The larger steel tanks can be over 100 pounds making them impractical for most people to tote around.
You can buy a new tank or possibly find a used one for sale but the 20 pound tanks are hard to find used. You can probably buy one at your hydro store but expect to pay more than a new tank from Amazon.
As far as refilling just about any welding supply store can refill your tank. At the hydro stores you will usually swap an empty tank for a full one. It cost me $20 to refill my tank but it may be more in other areas. You will want to buy a tank with a built on carrying handle too.
You will also need a regulator. This will adjust the flow rate from the tank. It also has a solenoid that can open or close the flow. All regulators look about the same to me although I have a Titan Controls regulator. They range from about $50 to $80 new. You may be able to find a used one on Craigslist or somewhere like that.
You will want the micro tubing that comes with it. This tubing has laser drilled holes in it to allow the CO2 to disperse in your grow. You will hang it over your grow and because co2 is heavier than air it will fall onto your flowers. And you will also need a special fiber washer to install it to the tank. Most regulators come with these.
About Timers For CO2
Because plants only use CO2 during the day you will need a way to turn the solenoid on and off. If you have room on your light timer you can simply plug it into that. Otherwise you will need a separate timer so the solenoid closes at night and comes back on with the lights.
Some people use an interval timer set to run days only if you are going to run CO2 and fans to vent you will need this type of timer.
Why You Want A CO2 Controller
Without a controller you will have no way to know exactly how much CO2 you are adding. You could be under or over dosing it. A controller will open and close the solenoid on your co2 regulator based on your settings. It cost a bit more to get started this way but you will get better results and wont be wasting CO2.
CO2 controllers vary a great deal in price depending on what you want them to do. Some act as environmental controllers that can turn on fans or heaters or air conditioners and dehumidifiers.
I am guessing most of you dont want to spend a ton of money for these so I will take a simpler approach. I am going to recommend you at least get a monitor like this:
This is the unit I am currently using. It will give you temperature, humidity and co2 levels. It works well and is nice and compact and not too expensive. But remember it is not a controller just a monitor.
I just purchased the unit below and am waiting for it to arrive. It is basically like the unit above but has a remote sensor and allows you to set a desired ppm level.
Autopilot has a pretty good reputation and I still cant believe how cheap this controller is because everything else I found was pretty much over $200. I am not sure this deal will last so if you want a controller I would jump on it.
Autopilot APC8200 CO2 Controller Review
Here is an unboxing and review for the Autopilot APC8200. You can buy this on Amazon at https://amzn.to/2OXlVXC Cheapest and best basic co2 controller and monitor I have found.
LET ME MAKE ADDING CO2 EASY FOR YOU!
In a hurry and want to add co2 to your grow fast? Dont want to search all over for all the different components? Here is a co2 enrichment kit and a great deal I found on Amazon to get you started .
Before we start adding co2 we need to decide how we are going to do it. One way is by using intermittent flow and the other is a constant flow method.So there are 2 basic ways to go about it.
The first method involves using a timer for the solenoid and a separate timer for a fan. Generally speaking this is the most often recommended method. You use a chart like the one below to release your co2 as quickly as possible and then the solenoid shuts off. About 45 minutes later your fan, also on a timer kicks on for 15 minutes and then shuts down. Then the cycle starts all over again.
The typical level of CO2 in the air we breathe is 300 PPM. This timing chart will assist with adding an additional 1200 PPM of CO2, bringing your garden area’s CO2 level to 1500 PPM, which is considered ideal for most indoor gardens.
Along the top row of the chart represents cubic feet (CU.FT) of your garden area (length x width x height = CU.FT). The left column represents the Flowmeter setting (CU.FT/HR) which is controlled by the Flow Adjustment Knob. Simply determine your CU.FT/HR and set your Flowmeter. The chart will tell you how long to set your timer to bring your CO2 level to 1500 PPM. EXAMPLE: If you have 800 CU/FT and set your Flowmeter to read 6. It will take 10 minutes to bring the CO2 up to a level of 1500 PPM.
Ideal CO2 enrichment times range from 8-15 minutes. The quicker you can replenish the CO2 in your space the better. CAUTION: Excessive flow rates of CO2 from a tank through a regulator can cause the regulator to freeze and can permanently damage the regulator. Your garden area will determine adjustments made to this timing chart (plant maturity, drafts, leaks, etc. should be considered). Some gardens will require less time than indicated and some gardens will require more. http://sunlightsupply.s3.amazonaws.com/documents/product/702710_Instructions.pdf
This method will work but it could take some fiddling to get the timing just right. Also I think 1200 ppm is plenty and the old recommendation of 1500 may be outdated especially considering ambient co2 levels are now about 400-450 ppms and not 300. Global warming IS saving you money on co2 LOL!
I am using a constant flow. I have my flow adjustment knob set as low as it will go. So the little green ball is setting at .o5. In by closet (3 x 6 x 8) it gives me a level of 1200 ppm. Your results may vary depending on size of area and tightness of the space.
I dont like the idea of dumping it in fast and it seems you have a lot of gas leaking out before the plants can use it. Instead I want to trickle in a steady level plants can use. I think synching fans with your regulator could drive you crazy and I dont think it is practical if you are using a controller because they are designed to maintain a constant level of co2.
Hooking Everything Up
The main thing you want to watch for is leaks. Make sure your tank is all the way off. To install the regulator you will want to screw the regulator nut onto the tank. Pulling back on the rod will make it easier to thread the fitting on. Dont forget to use the washer or it will leak no matter how much you tighten the fitting.
Once it is installed turn the tank on. Plug in the solenoid and then use the flow adjustment knob until you see the green ball start to float. Then spray the area where the rod comes out of the fitting with some soapy water. If you see any air bubbles you will need to tighten things down until there are none.
The next thing is to install the tubing that came with the regulator. Since CO2 is heavier than air you will want to get as much of it as you can above your crop so co2 rains down on it. If you dont have this tubing you can use 1/4″ airline tubing and run it to the back of an oscillating fan.
Dialing It All In – Controlling Temperature And Humidity
First things first. You want to know where your co2 levels are at. Use a monitor or controller. If you cant afford one you probably should not be running co2 until you can. In a pinch you can go by the chart I provided but you still will only be guessing at your levels. In the long run a controller will save you money on co2 usage and trips to refill your tank.
You are going to need things to run for a bit so you can see what the temperature and humidity are. In my situation my temps run in the upper 80s and humidity is 50-55% but this will vary greatly from grow to grow.
At this point I do not need a dehumidifier or air conditioner but when summer rolls around I will probably run from midnight to noon because overall temperatures will be lowest then.
I wish I could guarantee all this will work without a hitch but I cant. You may still need to run an AC. The good news is an AC will also help control humidity.
For a small space running a mini split is not really an option so what you will need is a portable AC with 2 hoses. This will pull air in and exhaust heat without sucking out your co2. The units by seem to have good reviews. I am not an ac user so I cant help you size one or chose a brand. All I can tell you is make sure it has 2 hoses.
Venting Your Grow
At some point you are probably going to need to vent your grow space. First lets deal with heat.
HPS Vs LED
If you are running LEDs heat probably wont be much of an issue except on the hottest days.If you are running HPS you will absolutely need an air cooled grow hood.
Not only that, but you will need to pull air from outside your grow tent. You will also need to exhaust it to the outside. So it is an air flow that is totally separated from what is going on inside your grow room. This is a good practice even if you are not running co2.
If you are going to grow you need to control the smell. Period. Dont think for a second that just because you dont smell anything no one else can either.
With HPS you will need to exhaust through a carbon filter placed outside your tent. If you are running LED lights you can put a fan on top of your filter and pull the air in the room through it. So you will be recirculating everything without needing an external exhaust.
Getting The Temperature Under Control
The good news is that running CO2 allows you to run your temperatures 5-10 degrees higher. Usually about 76 is considered good for HPS. We are talking about leaf surface temperature (LST) here and not room temperature.
For LED grows you want a LST of 82-86 degrees and some research says 86 is optimal for plant photosynthesis. With that in mind heat should not be much of an issue. When I was running an exhaust fan I actually had to add heat most of the year.
I dont know if this can be taken up the same 5-10 degrees like running HPS. So far I have hit 91 with no adverse affects. This usually does not happen until the last few hours of my cycle. For most of the day I am 81-86.
When I first started this experiment I was running a passive exhaust 24/7. I disconnected my exhaust duct and left it open. My fan continued to run sucking through my carbon filter and blowing the air back into the closet. I experimented with running the passive exhaust open and closed off.
It worked fine but I did not see a need to exhaust at all because temps and humidity were pretty good so why exhaust co2 when you dont have to? I may need to go back to this when things warm up this summer and since heat rises and co2 sinks it only seemed to reduce my ppms by 2-300. So instead of being at 1200 I was at 1000 ppms.
This setup might be all you need to control temperature and humidity. Again I just want to say every grow space is different and climates are different too. Since I am in Western Washington temperature and humidity are pretty moderate most of the year. Humidity is low in the winter when the heat is on and low on sunny summer days too.
I run my exhaust fan at night to get odors , temps and humidity down on my off cycle. This works really well. I could probably set it to go on for a few minutes during lights on. I have tried this and it does not seem to remove much co2. My levels only drop about 2-300 ppm over 15 minutes. My fan is on a fan speed controller and I run it low because it is oversized for my closet.
I am just using a pin timer at this time. If you want better control you will want to use a fan speed controller like the Mercury 4 that can be set to turn your fan on and off at a set temperature and can also control fan idle speed.
One final option is to get an environmental controller. These are often run in greenhouses. They can be expensive but they allow you to synch your co2 with fans, heaters, and dehumidifiers too.
Adding CO2 To A Grow Tent Or Closet
Well that’s about it for now. You can add CO2 to a vented grow despite what all the naysayers tell you. I will continue to update this so you be able to follow my progress. If you have questions leave a comment and I will do my best to answer them.
Happy Growing. Stay Green