Maximum Yield USA May 2018 | Page 67

W e often use many scientific methods for indoor gardening, often without even knowing it. It may not occur to us we are using and learning not only about biology, but chemistry and physics as well. With indoor growing, the aim is to mimic the environment the plant would naturally grow in, while also trying to optimize that environment so the plant achieves its maximum potential. The controls we use are also intended to make the process as easy for growers as possible, allowing us to get great yields easily and with the greatest convenience and minimum fuss. Given that, it’s interesting to take the idea of negative pressure in the growroom, look at how to achieve it, and assess the science behind it. The force of the air escaping will send it flying off ground the room. Similarly, if it is pierced it will make a loud bang as all the air rushes to escape through the tiny hole. If you pierce a water balloon, the liquid will squirt out like a jet from the positive pressure force trying to escape the balloon. Negative pressure is simply the opposite, so an enclosed area has a lower pressure than the area surrounding it. A good example is a drinking straw. When you suck on the straw you create a vacuum or area of negative pressure by removing the air from the straw. To relieve or fill that negative pressure, fluid (your drink) or more air rushes into the straw, just like fluid rushes out of the balloon when you puncture it. Understanding Negative Pressure Negative Pressure in the Growroom Never heard of negative pressure? Could you explain it to someone if you had to? Pressure is defined as an area of force. Positive pressure is when an enclosed area has higher pressure than the area around it, so the gas or liquid inside of it is pushing to get out. A balloon filled with air or water is a good example. Air wants to and will escape from the balloon if you let it go as you are blowing it up. “Keep your tent in negative pressure for the entirety of your grow for best results.” So how does this apply to your growing regime? Your growroom is a perfect example of an enclosed environment and your ventilation system is the air source being sucked in and expelled out. An area of negative pressure is created inside the growroom by the rate at which air enters and leaves the environment. grow cycle 67