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So, you’ve got everything nailed down – you’ve mastered your lighting, environment and feeding and you’re pulling in large quantities of high-grade produce. What next? Well, if this is you, the thing to investigate is carbon dioxide (CO2) supplementation.
CO2 levels are one of the key factors that dictate rates of photosynthesis. Plants take the CO2 from the surrounding atmosphere and break it down into its component parts of carbon and oxygen, using the light energy from your grow lamp (or the sun) and a magical molecule called chlorophyll. The carbon is then used to manufacture essential plant sugars and the oxygen is released as a by-product.
Typical ambient levels are around 360ppm, but plants can make full use of at least three times that level before they become vulnerable to toxicity. By increasing the concentrations of CO2, plants are able to produce more sugars. This in turn accelerates overall growth rates, causing fruits to swell in size, while making plants more resistant to higher temperatures. It comes as little surprise, then, that CO2 supplementation is used extensively in the professional horticultural industry.
Luckily, we’re stocking the Pro-Leaf Controller – an excellent little unit that makes it easy for smaller scale growers to regulate CO2 in a plug-and play fashion. It works by telling your CO2 generating equipment when to switch on and for how long. The basic concept is no more complicated than that of a typical fan speed controller. However, instead of selecting an ideal room temperature, you choose a CO2 level in ‘parts per million’ (PPM). The Pro-Leaf features a professional-grade sensor that continuously monitors the grow space. Data on CO2 concentrations is then fed back to the Pro-Leaf’s onboard computer, and if levels drop below your ideal setting, CO2 is dosed as required until the levels return. It’s that simple.
What Other Equipment Will I Need
We won’t go into the full details here, but as a rough outline, you can choose between CO2 cylinders (known as cold CO2) or gas burners (referred to as hot CO2).
Hot CO2: The Autopilot CO2 Generator. Choose between natural gas and propane models. Connects to a gas bottle and plugs directly into the Pro-Leaf. Gas is burned when required, creating CO2 as a by-product.
Cold CO2: Dimlux Regulator and CO2 bottle. The regulator fits onto a CO2 cylinder and plugs directly into the Pro-Leaf. The regulator’s solenoid valve releases CO2 when needed.
We recommend opting for cold CO2 wherever possible, because hot CO2 generates additional heat, moisture and unwanted gasses as by-products.
How to Set Up a CO2 Controller
Setting up the Pro-Leaf is about as easy as it gets. Plug your CO2 generating equipment into the Pro-Leaf, then plug the Pro-Leaf into a power socket and choose your settings.
The team behind the Pro-Leaf have made some improvements since we filmed our video. The unit is now powered with a 3-pin UK plug. The socket that’s used to run your CO2 equipment now comes with an adapter that will fit both 2-pin and 3-pin plugs, so it can handle any of your CO2 generating equipment, straight out of the box.
Mount the unit at least 8ft away from any equipment that generates large levels of electrical noise and hang the sensor in the middle of the room using the supplied hanger. Note that the sensor isn’t waterproof, so be sure to move it out of the way when administering foliar feeds or pest prevention. It comes with a built-in photocell – whenever your lights switch off, CO2 dosing stops automatically. This is important because any CO2 administered during dark periods is wasted, since plants need the light energy from your grow lamp (or the sun) to make use of it. The Pro-Leaf is designed to commence dosing the very second it becomes beneficial to do so, and not before.
Next, you’ll need to choose your settings. The Pro-Leaf keeps it simple, featuring only two knobs and a switch.
Press the left dial and it will bring up the PPM setting, which defaults to 1000 PPM. For more info on choosing the right PPM visit the blog, but 1000 PPM is a great starting point. Push the right dial to bring up the Deadband setting. This setting decides how responsive the controller is to changes. The default is 50, which tells you how far the controller will allow CO2 levels to deviate from your chosen setting before triggering your CO2 source to switch on. It works in the same way as the hysteresis setting that you’ll find on many fan speed controllers. Think of it as ‘responsiveness’. Choose 50 as your setting and the controller will allow room levels to deviate by 50 PPM before dosing.
Lastly, you’ll need to set the switch in the bottom right-hand corner to the correct setting. Choose ‘PPM UP’ if you’re using a ‘hot CO2’ generator or choose ‘FUZZY LOGIC’ for a ‘cold CO2’ cylinder and regulator. Make sure that you choose the correct setting! Fuzzy logic prevents your CO2 regulator from freezing up by dosing in shorter bursts.
There’s a third setting available called ‘PPM DOWN’, but this setting won’t be used too often for indoor growing applications. As the name might suggest, it’s more useful in situations where you need to reduce CO2 (not increase it), and it works by switching fan equipment on whenever CO2 concentrations get above your chosen setting.