Digital ballasts are the best option for professional indoor gardeners - they’re more efficient than magnetic ballasts, have a higher output and prolong the life of the lamp due to the higher operating frequency. In the hydroponic setting, you only really need to be concerned about ballasts for your High Intensity Discharge (HID) lighting, since fluorescents and LED’s normally use on-board drivers or ballasts that are internal to the unit. Read our buyer’s guide below for more info on digital ballasts.
Digital ballasts are slowly replacing the old magnetic ballasts in a range of applications due to the fact they’re superior in a number of key areas.
Digital ballasts are much lighter and smaller than magnetic ballasts so they’re much easier to install or remove - there's also less weight to think about if you're in a tent as most tents are rated with a maximum hanging weight. Digi ballasts are also dimmable so you can run lamps at a selection of outputs depending on the requirements of your plants at the time. Another benefit of digital ballasts is that they are more efficient, outputting less heat and using less electrical energy. This means your extraction does not have to work as hard to maintain temperatures that facilitate plant growth. Digital ballasts run silent with no reliance on magnetism that can cause components to vibrate leading to a humming noise.
The only downside to digital ballasts is the radio interference that can be generated. The extent to which this RF interference interacts with different electronic equipment seems to be highly varied - with several factors affecting the degree of interference including: What your walls are made of, how thick your walls are, the amount of shielding included in the unit by the manufacturer, the frequency the ballasts are running at and the number of digital ballasts.
Whilst you can use higher power bulbs on a dimmed ballast, it’s not recommended because the spectral output of the lamp will shift as the elements within the bulb will be excited to a different level than what the manufacturer intended.
Most Digital ballasts have an ‘overdrive’ function which allows the bulb to be pushed an extra 10% on top of its rated running capacity. This causes more lumens to be produced at the expense of bulb life. This function is particularly useful when the bulbs life is coming to an end and the output is starting to decrease as the extra watts can boost bulb output without having to change the bulb meaning you can finish your current cycle whilst maintaining an abundance of light for your crop.
Magnetic ballasts still work so if you’re just starting out, don’t let the downsides of magnetic ballasts dissuade you from buying one - they’re the cheapest initial outlay to get your garden producing but once you’ve got some cycles under your belt, you’ll appreciate the extra flexibility and lower running costs a digital ballast can give you.