We all want to maximize the potential of our grow rooms and a big piece of the equation is your grow lights. Choosing between magnetic or digital ballasts to run your lights is a serious question to consider. In many cases, switching from magnetic to digital ballasts offers the opportunity to improve lighting but this might not be the right move for everyone. Here we will consider the pros and cons of both ballasts types and hopefully make it easier for you to choose between magnetic and digital ballasts for your grown room.
I could go into the technical details of how a ballast works but the bottom line is that HID lights light HPS and MH require a ballast to provide the high voltage needed to ionize the gases in the bulb and then maintain steady voltage to keep the bulb glowing consistently.
There are two primary types of ballasts available for indoor grow lights but there is more than one term used. First there is magnetic ballasts, also known as core and coil ballasts. Second there is the group of ballasts referred to as electronic ballasts or digital ballasts. These are just different names for the same things but here are a few of the pros and cons of each.
Advantages of Magnetic Ballasts
Cost of Ballast and Components
The components in a magnetic ballast are simple and cheap which makes magnetic ballasts inexpensive both to buy and fix. They have also been around for a long time so there are plenty of suppliers to choose from and if you are on a tight budget, there are usually plenty of used ones on the market.
Ballast Lifespan
Magnetic ballasts are durable and usually run problem free for many years. You’re not going to take one out of the box only to discover it doesn’t work.
Ease of Maintenance and Repair
There are only a few components inside a magnetic ballast so if something breaks you can usually replace the part for cheap or if you are not particularly handy, most grow shops can do it for you in a few minutes. If you are running a lot of lights, you can stock spare parts so your lights are never down for long.
Disadvantages of Magnetic Ballasts
Noise
Magnetic ballasts tend to make a buzzing sound which can give away the grow room if you are trying to keep it a secret. It can also be annoying if you are working in the grow room for long periods of time.
Heat
Magnetic ballasts are not super energy efficient so some of the energy they consume is wasted and just turned into heat. You really want this electricity turned into light since you’re paying the electric bill. Extra heat accumulates and often needs to be removed with fans or an AC unit. Now you’re paying for even more electricity.
Heavy/Bulky
Magnetic Ballasts are heavy and rather bulky. They take up space and can be awkward or difficult to mount on walls or ceiling without and extra pair of hands.
Advantages of Digital Ballasts
Electrical Efficiency
Magnetic ballasts generally use between 1100-1200 watts of electricity to to run a light rated at 1000 but an electronic ballast should use only between about 1050-1100 watts. By wasting less electricity, you are getting more light for less utility bill.
Cooler Running Temperatures
Because less energy is wasted and turned to heat, electronic ballasts run cooler and won’t add nearly as much heat to the grow room.
No Ambient Noise
Electronics ballasts don’t produce the buzzing noise of magnetic ballasts, so, in many cases they can be installed outside of the grow room. By doing this, the heat they produce won’t need to be removed from the grow room with fans or AC which adds to overall efficiency.
Variable Bulb Types
Most electronic ballasts can automatically adjust themselves for use with both Metal Halide and High Pressure Sodium bulbs. While some magnetic ballasts are “switchable”, and can run both bulb types, you will usually need to remove the cover and flip the switch manually. If you are running a lot of lights and switching bulb types during every cycle, this can be a lot of extra work.
Bulb and Wattage Versatility
Electronic ballasts usually have a built in dimmer switch allowing growers to run lower wattage. This can be handy for giving your plants an easier transition for the first few days after transplanting. Some electronic ballasts can actually run lower wattage lights as well. I’m sure you can see the advantage of a ballast that can automatically adjust for HPS and MH lights as well as run 400, 600 and 1000 watt bulbs.
Bulb Age Compensation
As bulbs age they tend to lose their strength. Eventually you’ll want to replace the bulb even if they haven’t burnt out. The hard part is knowing when to change the bulbs. Wait too long and your garden suffers but change them out too soon and you’re wasting money on bulbs. Electronic ballasts can compensate for the aging bulbs which makes them produce the same light output even as they get older.
Restrike Time
When a grow light has been on for some time and then turned off, it cannot be immediately turned back on. The arc tube must have a chance to cool down before the lamp is turned back on or the grow light will not restart. This period of time is called the restrike time. Because of their more advanced electronics, e ballasts are able to “restrike” or relight a hot bulb sooner. This can be a time saver when needing to turn lights off and back on.
Disadvantages of Digital Ballasts
Extra Cost
Because of their complexity, electronic/digital ballasts are considerably more expensive. While I’m sure there are exceptions you are probably going to spend at least twice as much for a quality digital ballast. For example, here is a high qualify Hydrofarm magnetic ballast for $97 and a high end Phantom digital ballast for $299. Both will run a 1000 watt light but if you are buying high quantities or on a tight budget, this is something to consider.
Bulb Compatibility Problems
Some digital ballasts just don’t like some bulbs. I’m not sure I fully understand the reason behind this but my experience as well as that of others suggest that some cheaper bulbs just don’t run well on electronic ballasts. That being said, I have never had trouble when using both a higher end bulb and a higher end ballast.
Ballast Lifespan
Electronic ballast die when they get too hot. While some do a great job at dissipating heat through the use of heat sinks, others rely on cooling fans. The problem with cooling fans is that they have moving parts and if the fan fails, the ballast dies.
Radio Frequency Interference
Electronic ballasts can create radio frequency interference which can cause problems for both the electronics in your home and those of nearby neighbors. If you are running an undercover grow room in an area with close neighbors, this can trigger a knock on the door from the cable company, or worse. Some brands have done a better job of RF shielding their units than others. While one ballast might not cause a problem, 10 of them together could be a big deal.
Pro Tip
You can test your grow room for a potential RFI problems yourself. While not exactly cheap, Multi-Field EMF Meters are readily available and are lot less expensive than posting bail. If it looks like your ballasts are causing and RFI problem, you can shield them with a nickel copper signal blocking fabric. While it may be too expensive to sheath your whole grow room, try creating a smaller space to house your ballasts and lining the area with the signal blocker.
We hope our thoughts on the topic will make choosing between magnetic and digital ballasts an easier decision. For more reading on setting up the grow lights in your grow room, check out Grow Light Intensity Principles and Light Cycles and Flowering Cannabis.
Choosing Between Magnetic and Digital Ballasts,
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