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A Brief Rundown of Metal Halide and HPS Grow Lamps

MH VS HPS LampsDo you plan on doing some winter gardening? Perhaps you are just curious if you could be getting better results out of one bulb than another? No matter if you are bringing the crops in from the cold or just interested to see which bulb glows the prettiest, Advanced LED Lights has you covered.

If you haven’t guessed by now, this article is an overview of Metal Halide and the High Power Sodium lamps.

Grow efficiency

Chances are you are probably using the same sun as the rest of the world; and while it would radiant if we could place the sunlight only when and where we needed it, that has yet to become a reality. Using a Metal Halide bulb (or MH for short) or a High Power Sodium may be a great alternative to start increasing your growth, maintaining your space, or just simply increasing your maximum yield.

What are the differences between the two?

Both the Metal Halide and the High Power Sodium are High Intensity Discharge lamps or (HID). That means that both will use ballasts, capacitors, ignitors and/or power supplies to correctly operate. HID Lights are especially known for their arc tubes, which basically generates light though the excitement of chemicals within the arc tube itself. HPS lights contain strictly sodium within its arc tube causing the HPS to emit a very bright orange/yellow spectrum (2200K). Likewise, the excitement between the 2-5 chemicals contained within the arc tube of a MH light emit blue/green/white light from its spectrum (2700-5500K).

Another simple way to distinguish between a MH or a HPS is a Metal Halide bulb typically appears much fatter than High Power Sodium bulbs which tend to be skinnier and taller depending on which brand you buy. (This can vary greatly between Brands so for now lets stick to the generalizations.)

Types of LED Grow Lights

Which light do I chose and why?

Because plants have different stages of growth, controlling the spectrum, power, and timing is vital to ensure maximum results. In the beginning stages of plant growth MH bulbs work great with juvenile plants causing them to flourish during the vegetive stage augmenting tight dense foliage and plants that are strong and stocky. On average Metal Halide bulbs typically last for 1.5-2 years of 18/hours a day.

As plants reach the flowering/fruiting stage the HPS spectrum enhances the quality of fruit and a larger harvest. The HPS spectrum mimics the outside autumn light increasing the plants demand for light. At this stage growth continues exponentially causing plants too become wider and more open.

Can I use the same ballast for both bulbs?

Unfortunately not all ballasts allow both the MH and HPS bulbs to be interchangeable. While some do, it’s never a good idea to assume both can be utilized. This being said, placing a 1000 watt bulb in a 400w System must never be done! Likewise you should never put the opposite bulb in its adjacent system as ballasts are only meant to support the bulb in which they were created for unless otherwise stated by the manufacturer. However, it is possible to swap out both a MH and an HPS with the use of a Conversion bulb. Utilizing a conversion bulb would (in most cases) cause you to run the MH during the vegetive stage of plants life, then switch to a Sodium conversion bulb for the simulation of fall, or Harvest. Also, with conversion bulbs you don’t have to switch out the ballast and reflector, Solely the bulb.

Any other dangers I should know about?

Why yes, I am glad you asked. If you have successfully gotten through the ballast phase, a few key warnings are important enough to mention.

HID bulbs contain mercury, Which is very toxic and in some cases deadly due to its extremely poisonous properties. Use caution when handling any HID bulb.

HID Lamps and their corresponding arc tubes get extremely hot! This causes them to be a risk for shattering in cases of a system failure, improper installation, or other factors. This can send projectile glass soaring through the air causing cuts, risk of initiating fires, property damage, or Electrocution. Lighting should always be turned off and/or locked prior to removal or maintenance of either Light.

I hope I have enlightened any questions you may have had about the HPS vs MH. Whether you decide to go with the HPS or the MH We wish you the best at Advanced LED Lights. For our products, videos, or more articles please visit us at

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