Grow Light Basics, Part 3

Part 1 of this series covered bulbs and lamp coverage; part 2 covered grow fixtures and timers. In the final chapter, we will be discussing ballasts. There are a wide variety of ballasts to be used with different types of bulbs, different wattages, and different set ups. If you are trying to find the right ballast for your growing needs, stick around and see if we can answer your questions.

Fluorescent Ballasts

If you are using fluorescent tubes for your indoor grow, make sure you use a fluorescent ballast. As stated in part 1 of this series, T5 bulbs are used often for indoor grows, so be sure to double check the lamp type. Once you have determined the size of lamp; you will then need to determine the start method. Instant start ballasts do not preheat the electrodes; they are best if the lamps need to stay on for long periods of time. Programmed start ballasts heat the lamp cathodes slowly; allowing for a longer lamp life, and rapid start ballasts apply voltage and heat cathodes simultaneously. Lastly, consider the ballast factor. For bright lighting, use a high output ballast with a ballast factor above 1.1, for low lighting, a low output ballast with a ballast factor of 0.77 is best.

Magnetic Ballasts

Magnetic ballasts are used with both metal halide lamps and high pressure sodium lamps. They regulate the starting requirements, as well as the line voltage for specific lamps, delivering stable power to the lamps. When using a magnetic ballast, be sure to use a lamp that is at a wattage equal to or less than the ballast wattage.

Some metal halide lamps are pulse rated; they feature a high-voltage ignitor that work with the ballast to start the lamp utilizing a series of high-voltage pulses, generally 3 to 5 kilovolts. The ignitor reduces the amount of tungsten sputtering, as well as warm up time, to increase the life of the lamp. If you use a pulse start metal halide bulb, be sure to double check the ANSI code of the ballast to ensure the pulse rating of the ballast works with the bulb.

Digital Ballasts

Using metal halide and high pressure sodium lamps? Digital ballasts are the best way to go! These lightweight ballasts operate both types of lamps, detecting the lamp inserted at that time, and will run the lamp to ANSI specifications. They can be dimmable and also run quietly without the hum of magnetic ballasts. While most digital ballasts operate both metal halide and high pressure sodium lamps, some only operate one or the other. In this case, you can either use the specified lamp, or a conversion bulb.

If you have any other questions regarding ballasts, fixtures, bulbs, or any other accessories for your indoor grow, be sure to let us know in the comments or reach out to us on Facebook and Twitter!