Digital and Magnetic Grow Light Ballasts
If you choose to grow with HID lighting, you will need a ballast to drive the lights and for them to properly operate.
A ballast is a device that interacts with a lighting unit, such as a lamp, and controls and regulates the voltage, current, and waveform. In other words, without one, the lamp would overheat and burn out.
When deciding upon a ballast, you will need to pick one that meets the requirements of the lamp, which will result in the best light output and give the lamp a longer life. The manufacturer will provide you with such information.
Digital vs. Magnetic Ballasts
There are two main types of an HID ballast, digital and magnetic, and they both have their pros and cons.
A digital ballast pros outweigh its cons, and most growers preferred them over magnetic ballasts, but it’s still important to look at them.
- More energy efficient
- Lower heat output and durability
- Some are dimmable
- Smaller size and weight
- Some can put out 30% more light
- Cheap digital ballasts have issues with RFI (radio frequency interference)
- More expensive
- While they produce more light, they will burn the lamps out quicker
- Can be picky about which brands of lamps they run
The number one issue with digital ballasts is they cause RFI or EMI (electromagnetic interference), and need RF shielding. RFI can cause serious issues for growers and can affect their cable as well as their neighbors’ cable, among other issues. A cable company will see that the issue is coming from your house when they are out working on the neighbors’ line. The ballast can also be picked up by using an AM radio, which is one way you can check if you’re worried your ballast is sending out radio frequencies.
This is why you do not want to buy a cheap digital ballast that has zero or little RFI shielding. A properly shielded ballast will cause no issues whatsoever, and you have nothing to worry about.
Magnetic ballast are becoming less and less common, but some growers still prefer them.
- Bulbs last longer
- They work great with any HID lights as long as the wattage matches
- Simpler and anyone with basic electronic know-how can repair them
- No issues with RFI
- Lower light output
- Hum or buzz when running
- Wattage specific – e.g. 500 watt ballast needed for 500 watt bulb
- May be specifically made to only handle a MH (metal halide) or HPS (high pressure sodium) with no switchable option
- Can run hotter
Usually, both digital and magnetic ballasts can be plugged into either a 120V standard house outlet or a 240V outlet. But it’s the dimmable option that many digital ballasts have that makes them great for growers of all types, and for different growth stages.
A dimmable digital 600-watt ballast, for example, may have the ability to be dimmed down to 400 or 250 watts. This allows you to not only mix different HID bulb wattages but also allows you to run a 600-watt bulb at a lower wattage if needed.
Some other nice features to look for are some ballasts come with warranties and an external breaker system to protect against power surges.
Grow Light Ballasts vs. Grow Light Bulbs: Which is More Important
The honest answer is both are equally as important.
If you have to cut cost on one, then surprisingly you should buy a cheap bulb before buying a cheap ballast. A cheap ballast will degrade bulbs faster, potentially have poor RF shielding, and have consistency and safety issues.
While you preferably don’t want a cheap bulb going into a high-quality ballast the opposite is considered a worse idea. Spend the extra money on both, however, and you will save money in the long run.