Best CO2 Regulators for Growing Cannabis

At the moment, atmospheric levels of CO2 are at about 400 parts per million (PPM). When growing cannabis indoors, you can raise the level of CO2 in the air to nearly 1500 PPM. With this level of CO2, your weed will flourish and your bud yield will rise by up to 30%. If you increase the CO2 level to more than 1500 PPM though, your weed will suffocate and eventually die.


Even with high levels of CO2, it is still important to move the air around within your grow space to make sure this level stays consistent. Make sure you invest in a good inline fan for this, and your weed will thank you.


Generators, Regulators and Controllers


There are two main ways to regulate CO2 levels in a grow room. You can either buy an all in one CO2 generator, or you can buy the parts separately to build your own system. What you will need is a source of CO2, a way to regulate this source of CO2, and a way to measure CO2 levels in your grow room.


Take into account how your source produces CO2. If you use a system that creates CO2 by burning butane or propane, then you will need to account for the extra heat this will add to your plants’ environment. An alternative is to use a tank of pre-obtained CO2 plus a regulator (which controls the release of CO2) and controller (which detects the amount of CO2 in the grow room), as this won’t add any extra heat into your grow room.


How much carbon dioxide do you need?


First, measure the size of your grow room (in feet) and multiply the measurements to get the cubic volume of your grow space. Then multiply this figure by 0.0015 (or 0.0013 if you don’t want to risk suffocating your plants) to find out how much flow you need. If you have a generator, check the cubic feet per hour (CFH) rating. Keep in mind that one pound of CO2 compressed in a tank is the same as roughly 8.7 cubic feet of gas once it has been released into the air.


You will then need to set your regulator for the correct flow rate and PSI amount, and you will need to set your timer so that your CO2 is only released during daytime hours (plants need more oxygen at night). Here is an example of the above calculations:


Let’s say your grow room measures 8ft by 8ft by 8ft, which is 512ft3. Multiply this by 0.0013 and you get 0.6656, or about 0.66 cubic feet per minute. This means you can set your regulator for 100 PSI and the flow at 0.33 cubic feet per minute (with a rating of 20 CFH). You will need to let the gas flow for two minutes to fill your grow space and then switch it off. You can repeat this every couple of hours whilst your grow lights are switched on to maintain optimum CO2 levels.


Why are timers important?

Timers are important both for you and your plants. You don’t want either one to suffocate! Using a tank regulator means that your grow room will be injected with CO2 for a couple of minutes every few hours whilst your grow lights are on. This is a somewhat cheaper option, as the machine doesn’t need to be running all the time.

You will also need to remember to turn it off when you turn your grow lights off, as plants need oxygen at night, not carbon dioxide. Timers can be useful to remind you to do this as well.

Now for some reviews. We are going to look at some of the top regulators available, so that you can find the best one for your system.


GRO1 CO2 Grow Room Environment Regulator Flow Meter Solenoid


This regulator is especially well suited to those who grow plants in aquariums, but it works just as well for those who grow marijuana. Its flow meter can be adjusted to between 0.5 and 15 cubic feet per hour, and it comes with a pre-set regulator and a long lasting solenoid valve.


SPL CO2 Regulator Emitter System with Solenoid Valve and Flow Meter

This all-brass regulator is durable and precise, and perfect for all weed growers. Its flow gauge can release between 0.5 and 15 cubic feet per hour, and is rated for anywhere between 0 and 4000 PSI.


It comes with a 6-foot power cord that requires 110V of electricity, as well as 10 feet of a ¼-inch-wide air hose which connects directly to a 20 or 50 pound CO2 tank.


Pro CO2 Hydroponics Regulator Emitter System

This all-brass precise regulator is designed specifically for managing and maintaining the flow of carbon dioxide for indoor growers. The Pro CO2 regulator can release between 0.5 and 15 cubic feet of gas per hour, and can handle up to 4000 PSI. It comes with a 10-foot long air hose and a 110V power cord.


ProLabs CO2 Regulator with Solenoid Valve

The ProLabs regulator has the same stats as the regulators mentioned above: it can withstand up to 4000 PSI and releases between 0.5 and 15 cubic feet of gas per hour. The power cord needs 110V of electricity, and it comes with a 4-year warranty. However, it does not come with an air hose.

Now that we have reviewed some regulators, it is time to review one of our favourite controllers. Once you have something to release the CO2 into your grow room, you will need something to monitor those CO2 levels!


CO2Meter RAD-0501 Day Night CO2 Monitor and Controller for Greenhouses


Mount this controller inside your grow room and plug it into a source of electricity and your regulator so that it can continuously monitor the CO2 levels in your grow room. It will automatically shut down the CO2 supply when your desired PPM level is reached. You can set your desired PPM level in increments of 50 from 100 to 9950. It also has a light sensor which causes it to shut down when you switch off your grow lights.

Another option for controlling your CO2 levels is to get a ready-made CO2 generator. Instead of having to constantly haul heavy gas canisters around, a generator will provide you with all the CO2 you need there and then. Watch out though, generators will also add extra heat and humidity to your grow environment.


CO2 Generator – Liquid Propane LP – Autopilot APCG8LP

This generator is a powder coated steel enclosure that burns either propane or natural gas to create carbon dioxide. It is designed for large grow rooms of 14 feet by 14 feet or bigger, and it can raise the grow room temperature by up to 10 degrees Fahrenheit while it is on.

It emits up to 22 cubic feet of gas per hour, and has a smart controller which makes sure it only runs when needed. Finally, it has a safety feature which causes the generator to switch off if it tips over.

Finally, here are some accessories you might find useful with your CO2 setup.


Cyl-Tec 20lb CO2 Tank – New Aluminium Cylinder with CGA320 Valve

This 20lb CO2 tank keeps the gas at 1800 PSI and comes with a brass CGA 320 CO2 valve, and a male thread ready to be attached to a regulator. It has a carrying handle to help move it around, and the gas inside can be used both for growing and for carbonated drinks.


AcuRite 00613 Indoor Humidity Monitor

It is wise to purchase a temperature and humidity gauge when growing indoors, especially if you have a CO2 generator that will add heat and moisture to your grow room as it runs. This gauge is battery operated and therefore wireless, and has an easy to read screen, even in direct light.


Amflo 24-25E-RET Blue 120 PSI Polyurethane Recoil Air Hose ¼ inch width 25 feet length MNPT Swivel Ends and Bend Restrictor Fittings


This blue air hose is 25 feet long and ¼ of an inch wide, giving you more mobility with your CO2 setup. The restrict fittings ensure that no air is lost in transit, and it coils up neatly when you need to store it away.


Exhale 365 – Self-Activated CO2 Bag Home Grown for Grow Rooms and Tents


If you only have a limited grow space of no more than 4 feet by 4 feet in size, then this Exhale bag can help you to add CO2 to your grow room. Hang it just a little higher than your plants, and don’t forget to replace it every 6 months.



Summing Up

Monitoring and regulating the CO2 levels in your plants’ environment will increase the growth speed of your plants and the yield of your bud. Be careful not to flood your grow room with carbon dioxide, as this will kill your plants. Also be careful when using a generator to source your carbon dioxide, as this will increase the temperature and humidity levels in your grow space.

Whether you decide to build your own CO2 setup or buy an all in one regulator, make sure you regularly check back on your plants to make sure they are growing healthily. Don’t forget to check your machinery too. Happy growing!