Hydroponics or hydroponic gardening refers to specialized equipment used to grow plants without soil under plant grow lights. Hydroponics in Greek translates to Hydro = Water and Ponos = Work. Hydroponics literally means "Water Works". Here is what you need to know to not only get started but also maximize your results:
Carbon dioxide (CO2) was the first of the gases to be described as separate from air. CO2 can come from us, as we breathe out CO2 with every breath. It can come decomposing organic materials or from burning carbon based fuels. CO2 is very important to plants. Plants use CO2 during the process of photosynthesis (the conversion of carbon dioxide and light energy into simple sugars and the transpiration of water). That's right, plants only breathe in carbon dioxide during the day cycle. You can supplement carbon dioxide during the vegetative stage, cloning stage and during your flowering phase, but not during the night period.
Outdoor ambient CO2 levels are 250-400 PPM (parts per million). The ambient level is more than enough to grow healthy plants. However, increasing the level of CO2 can help make your flowers larger, heavier, finish faster or grow in a higher temperature environment. There is little to no benefit of going beyond 1,500 ppm in your garden. Some say that 1,200 ppm is sufficient. Above 2,000 is Danger for people and animals. Know your level and be safe!
Using carbon dioxide is actually pretty easy. It's all about balance. Because plants only use CO2 during the day, we want to supply CO2 only when the lights are on. We can plug our regulators into a timing device or a controller. These will ensure that the gas only comes on when the lights are on. This is the balance that was aforementioned. First, You need to determine how fast the gas should flow out of the regulator (Flow Rate set in site tube on regulator) and how long your timed "on" intervals need to be (because the gas does not need to be constantly on), for your sized indoor garden. Hydrofarm has a great online calculator to make that finding that balance a little easier!
Depending on your room, sealed or vented, CO2 may have to be timed with your exhaust fans. CO2 is a cost and dumping it right out the window is expensive! In a vented room, the CO2 regulator is timed opposite of your exhaust fan. If you room is sealed, it's most efficient to use a Fuzzy Logic Controller that will maintain the proper ppm level. Most of the premium controllers will control your CO2, heat, cooling and Humidity and make sure only the appropriate device is running.