HPS – High Pressure Sodium Grow Lights Review

by | Mar 10, 2016

HPS technology sets itself apart from the rest with its modern design and superior properties. It’s deemed to be one of the best choices when it comes to the plant growing light. Both outdoor and indoor gardeners like using it to get consistent, big harvests. So it comes as no surprise that many people use HPS grow lights for growing cannabis.

These super-powerful grow lights have been used for years. They do not only ensure bigger yields but also tend to be easy to maintain. Even though you can reap a lot of benefits with this awesome light system, bear in mind that it requires a fairly high initial investment. Besides, it takes slightly more time for installation. It quickly pays for itself, though.

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All You Need to Know About HPS Grow LightsBuy High Pressure Sodium Grow lights on Amazon

In this comprehensive guide, we’ve collected all the important information that can help you pick the right HPS bulbs for your crops. We are going to guide you through various lamp types and sizes, as well as their features and applications. Additionally, you’ll get a few useful recommendations on what to take into consideration when shopping for HPS lights.

What’s a HPS Grow Light?

HPS (High Pressure Sodium) grow light is high-intensity luminosity that is emitted when electrical current passes through a narrow arc tube consisting of Xenon and a mixture of mercury and sodium vapor.

HPS technology plays a vital role in cultivating indoor crops today. It involves HPS bulbs that come in different shapes and sizes. They commonly get turned on via a pulse start. Note that the light spectrum of the HPS bulbs varies widely between different manufacturers and different lamps alike.

HPS Spectrum Output

By responding to the particular light spectrum, the plants grow and flourish. This physiological process is called photomorphogenesis. The yield you get at the end of the production cycle largely depends on the spectrum output.

With regard to the HPS bulbs, they give off a golden yellow light which maximizes flower and budding production. Those bulbs produce “usable” light that the marijuana plants can utilize. It is referred to as PAR (Photosynthetically Active Radiation) spectrum. That light can be anywhere from 400 to 700 nanometers.

HPS bulbs provide the following color spectrums:Buy iPower 1000 Watt HPS MH Digital Dimmable Grow Light System Kits via Amazon

  • Yellow: 570-590 nm
  • Orange: 590-630 nm, and
  • Red: 630-750 nm

Not all the light produced by HPS lamps is not inside that spectrum, though. They also give off infrared light which is useless for the plants, and it contributes greatly to the heat production.

You should also know that the HPS light goes through different spectrum ranges. Once you turn on the lights, they will feature the orange-red spectrum at approximately 2200 K (about 3500 degrees Fahrenheit). That spectrum is perfect for growing cannabis plants, especially during the flowering stages. When the starter triggers the xenon gas in the arc tube, the lamps turn sky blue light. Then the arc warms up the mercury and makes it light up, emitting a bluish color. As the HPS bulb heats, the sodium begins vaporizing and mixing with mercury or other components in the tube, creating a white-yellow light. That’s actually the grow light you get when hitting the power switch.

The majority of today’s grow lights are available with both full spectrum and dual spectrum bulbs. Those are meant to generate the optimum output spectrum in order to meet the requirements of the plants. There’s lots of marketing and hype these days, which is why we’d recommend that you only purchase the bulbs from the well-known trusted brand names. Otherwise, you may easily end up with the low-quality bulbs that don’t worth the money at all.

HPS and/or MH Light Bulbs

Some growers add the metal-halide (MH) lamps, which have a green-blue spectrum, apart from HPS bulbs to get the well-balanced spectrum output and achieve the best results. That bluish bright light simulates the real spring sun and thus promotes the bushy short growth of the plants. Buy Sun System Grow Lights - HPS 150W Complete System with Ultra Sun Lamp via Amazon

While metal halides are ideal for the veg phase of growth, the high-pressure sodium light bulbs are more suited for the flowering phase when plants start to produce buds.

Metal-halide lights aren’t as strong as high pressure sodium lights, as they provide up to 115 LPW. Nevertheless, they are more powerful in the blue spectrum range, which actually promotes growth in plants. That’s why metal halides are helpful for vegetative stage.

It is a truth that you can use either HPS or MH lights during the whole production process and obtain good results. However, if you want to get the most out of your crops, we recommend interchanging these two types of bulbs. That will make a huge difference to the spectrum output and your plants as well.

HPS/MH bulbs emit the type of light that is beneficial for plants that have high light requirements such as cannabis. The mix of both HPS and MH lights appears to mimic the sunlight almost authentically, making the buds feature more complex terpene (smell and taste) profile.

One might ask: What it the right moment to shift from MH to HPS lights? A good rule of thumb is that metal halides are most favorable for relatively young plants with just stalks and leaves. Once the first buds have appeared, you may switch to the HPS lights.


Why Are HPS Grow Lights So Popular?

Why Are HPS Grow Lights So PopularMany growers chose the HPS technology due to the fact that it implies such a light that cannabis plants use well. It is especially beneficial for blooming, flowering, and fruiting plants.

There is a broad range of HPS bulbs to pick from. With so many different sizes out there, you can easily find the bulbs that suit any indoor garden. Even though there are 150-watt bulbs and 250-watt HPS bulbs, they often come with the own reflectors and ballasts in the all in one kit. As for the size, the most widespread bulbs on the market are 400 W (the most common), 600 W (the most efficient), and 1000 W  (the most powerful). We are going to see later how to choose the right wattage.

When adding the fact that HPS bulbs are also very reliable and affordable, it doesn’t come as a surprise that they have a growing popularity among the weed growers throughout the world.

Pros & Cons

Before you run HPS lights, take a look at the main good and bad points. That will give you a better idea of what to look for.

Pros

  • Efficient – When we take into account the amount of light that is generated for a certain amount of electricity, HPS grow lights are considered to be one of the most efficient lights nowadays. They provide high PAR efficiency in comparison with CFLs and most other fluorescent lights on the market.
  • Work great – Many people regard HPS grow lights as the golden standard for growing marijuana. That’s because they give off the ideal light for the flowering and fruiting plants. These lights are proven to produce exceptional growth rates and high yields.
  • Powerful – Producing more than 140 LPW, HPS grow lights stand out from the rest. High lumen output means plenty of light for cannabis plants. In a matter of fact, they are capable of producing the heat amount as the equivalent wattage value of compact fluorescent lamps (CFLs), but you’ll get better results and bigger yields with HPS lamps. That makes a world of difference.
  • Deeper light penetration – This is another advantage of HID grow lights over the CFLs. Deeper light penetration contributes to the bigger growth and taller weeds. Buy VIVOSUN Hydroponic 600 Watt HPS MH Grow Light Air Cooled Reflector Kit via Amazon
  • Greater coverage area – In most cases, high pressure sodium lights provide greater coverage area than other grow lights.
  • Simple scale-up – They can be used for growing either just a couple of plants or hundreds of plants. That allows you to easily scale up your grow lights according to the specific needs. If you need the lights for smaller grows, the small 150W and 250W bulbs can do the job just fine.
  • Intuitive – Once set up, HPS bulbs are quite intuitive to use. That makes them perfect for beginners to quickly learn how to install and use them. Just make sure to purchase the bulbs with an inbuilt ballast and hood because they can be connected to a plug directly without using extra light tools or sockets.
  • Periodical adjustment – Throughout the growing cycle of your plants, you’ll need to tune the height of the bulbs only 3 or 4 times. Plus, you will need to adjust just one fixture instead of multiple small bulbs as with compact fluorescent lamps.
  • Easily available – We recommend searching for purpose-built grow lights. However, there are various HPS systems readily available. They come in different sizes and wattages for different spaces. You can find them at every turn. For example, the orange-tinted HPS lights are widely used for street lamps, as well as in sports halls, arenas, and car parks.
  • Reliable – HPS light bulbs can be trusted, as they have been around for decades. For all these years, they have been consistently good in performance and quality. HPS lights are designed to last for many years to come rather than being replaced after a few months or so.  
  • Don’t need an upgrade – Even though these bulbs suffer degradation gradually, they usually do not need an upgrade once installed.
  • Affordable – Maybe these lights are not the cheapest ones out there, but they are fairly priced and affordable. That comes into play when you need to buy a lot of bulbs at once.

Cons  

  • A lot of heat – One of the biggest drawbacks of the HPS lights is the heat emitted. These grow lamps produce lots of heat, which can be a big problem when you want to grow marijuana in a confined place. This is why you should place the bulbs at a greater distance from your plants. That will affect the power of lights, though. The greater the distance, the weaker the light is.
  • Need cooling or an exhaust system – Due to the great heat, good ventilation is a must when going for HPS grow lights. This is especially true when using bigger bulbs like 600W or 1000W lights. The 400W lamps can increase the temperature of your room by 10 to 30 degrees Fahrenheit, depending on its size. So it is absolutely necessary to have an outstanding ventilation (preferably air-conditioning) to exhaust the excessive heat out of your indoor grow space. When growing marijuana indoors, the ideal temperature is between 60°F and 70°F during the dark period, as well as between 70°F and 75°F during the light period.
  • Require a ballast – The flow of electricity must be regulated properly when it comes to HPS bulbs. Older ballasts tend to work on the magnetic systems and could be quite heavy and bulky. Fortunately, modern High Pressure Sodium bulbs imply digital ballasts that are light and small. In addition, they are often molded in the light housing. Keep in mind that ballasts commonly inhale extra 50-150 Watts of power.
  • Require a high grow space – As stated earlier, HID light bulbs must be placed far from the plants to keep them from overheating. That means your grow space has to be relatively tall. Whether you have a grow room or tent, it’s advisable that it is higher than 5 feet (1.5 meters) – Find the right tent for yourself Plantsily.com/grow-tent.
  • High initial investment – That can be a serious problem for people who run on a tight budget. Getting started with HPS means a high initial investment.
  • High amount of energy needed – If you will be using the 1000W HPS lights, for example, they will need a ballast anywhere from 100 to 150 Watts. That’s a significant amount of energy, which will affect your power bill notably. LEDs use about 55% of that energy to produce the same light power.

It could be difficult to buy them locally – The HIDs are specially designed as growing lights, which is why it’s only possible to find and purchase them in a special grow store or online.


What’s a Ballast and Why Do You Need One?

If you want to run an HPS light, it’s essential to fit the right ballast. Otherwise, you can experience any of the following two scenarios. The first one is to break the bulbs; the second worse case is to set an explosion up.

A ballast involves a special piece of equipment and refers to the power source for HPS bulbs. It takes both the electrical current and input voltage for regulating the pulses at a particular frequency. That way it enables the bulbs to run optimally and efficiently all the time, no matter the voltage out of the grow light system.

Some smaller models, such as 150W and 250W bulbs, come with a built-in ballast. However, remember that most models do not have it embedded. This is why you need it. When plugging the ballast into a wall socket, your bulbs will directly connect to the hood. Then the electricity that comes from the wall will be converted via the ballast into what is actually needed by HPS bulbs to ignite and operate.

Most HPS light systems use the light bulbs with a large base that cannot be connected to the regular sockets either. Instead, they’re using the sockets which require a specific ballast in order to begin and maintain the arc tubes for power. There are also ballasts that can be used for both HPS and MH bulbs.

When shopping for a ballast, be sure to choose one that’s compatible with the type of grow light you’d like to use. For instance, if you wanna run a 400W light bulb, you will need a 400W ballast as well. Same goes for other wattages, as you’re going to see below. Also, you need to consider the following factors:

  • Longevity
  • Bulb Protection
  • Dimming
  • Flexibility
  • Radio Frequency Shielding​
  • Low Noise​
  • Low Temperatures


Digital ballasts are deemed to be the best choice for growing cannabis because they provide extra options to control the electricity used and amount of light emitted. It’s critical to make a good ballast choice. Aside from the overall quality, you should also consider features and price.

The best ones are supposed to keep the bulbs working in an optimal way even if the input voltage suddenly gets changed for some reason.

Digital vs. Magnetic Ballasts

While digital ballasts are more expensive than the magnetic ones (for a few dollars), they use less electricity, run cooler, and produce a higher intensity of light. Therefore, the digital ballasts are more cost effective in the long run.

Plus, they’re compatible with most types of light bulbs on the market. On the other hand, the magnetic ballasts require special bulbs.

Your best choice is to get a ballast which is dimmable, digital and can support both HPS and MH bulbs.

Choosing the Right Wattage

It may be a hard task to determine how much grow light is needed to cover an indoor grow space or tent. That could be a daunting challenge for the first-time growers in particular.

Choosing the proper wattage is the key to success when growing marijuana indoors, so it’s highly important to make the right choice. There’s a wide range of HPS bulbs to choose from, ranging from small 150 Watt to 1000 Watt models.  

Below, you can find out what bulb sizes are the most suitable for certain growing areas. That will give you an idea of which HPS bulbs best fit your own grow space.

250W HPS Lights


These grow bulbs also come with their own reflector and ballast built in. Though it is not difficult to find 250 Watt HPS lights in the stores, it could be hard to find a stand-alone reliable 250W ballast. Note that these bulbs get hot after a while, so it’s necessary to use ventilation when running them.

  • Recommended growing area: 2.5’ by 2.5’ (0.75 by 0.75 m)
  • Minimal distance from the canopy: 10 inches (about 24 cm)

400W HPS Lights


This is the most selling and most used HPS light size today. It’s no wonder at all, since the efficiency of these bulbs is very high and the amount of PAR light is quite notable. On the downside, the things get pretty hot at this size due to the large amount of warmth given off.

They are available on the market as kits with a separate bulb, ballast, and reflector. You can also find them as all in one light fixtures, but they’re less common.

  • Recommended growing area: 3.5’ by 3.5’ (1.1 by 1.1 m)
  • Minimal distance from the canopy: 14 inches (about 30 cm)

600W HPS Lights


Delivering approximately 90,000 lumens, the 600 Watt bulbs are considered the most efficient size of all HPS lights. They convert the largest amount of electricity into a light that plants can use. Moreover, they feature the minimal relative waste and are most unlikely to induce light burns when cooled adequately.

  • Recommended growing area: 4.5’ by 4.5’ (1.4 by 1.4 m)
  • Minimal distance from the canopy: 18 inches (about 45 cm)

1000W HPS Lights


While these light bulbs are less efficient than 600W bulbs, they turned out to be more efficient than 400W ones. That’s why many growers wanting to upgrade their light systems go for multiple 600 Watt HPS lights rather than getting the bigger 1000W lamps.

  • Recommended growing area: 6’ by 6’ (1.8 by 1.8 m)
  • Minimal distance from the canopy: 24 inches (about 60 cm)

How long is a HPS bulb good for?

A better comprehension of why and when your light system requires light bulbs replacement can help you keep a high level of photosynthetically active radiation all the time in your grow room. That will eventually maximize the production and performance of your garden.

Of all the things you have to master when growing marijuana indoors, understanding how the light energy diminishes is imperative of keeping an efficient grow space. By placing your plants close to the source of light, you’ll automatically get the most out of your light system. Yet, the distance between plants and light bulbs isn’t the only thing to take into consideration with regard to the light diminishing. This is why you need to know how long the HPS bulbs are good for.

All light technologies are depreciating over time. That reduces the light energy which is usable for plants. Why does it happen? When the HID lamps are first fired, they receive a tremendous voltage pulse. That blast of initial voltage damages the lamps a bit every time you turn on the lights. After a while (usually after 8 months), the repetitious process of firing the grow lights makes the arc tube change its properties. That doesn’t only cause a color shift within the spectrum output but also lower the intensity of lights.

Your task is to replace the light bulbs in your light system from time to time to avoid this reduction. This raises the question: What is the right time to replace light bulbs?

That depends on the type of lamps you use in your light systems. Let’s say you use metal halide (MH) and High Pressure Sodium (HPS) lights. If so, keep in mind that the depreciation rate of MH bulbs is fast compared to HPS bulbs. That’s because of the specific components and metals in MH lamps. Metal halide bulbs will be depreciated about twice as much as HPS bulbs after around 20000 hours of use.

If you’re using MH grow lights in your system, be sure to replace these bulbs after 6-9 months of use. As for HPS bulbs, they depreciate due to the operation temperature, initial voltage, and the age. Their lifespan also depends on the type of ballast used. They usually start degrading in the blue specter first because of the compounds used. Nevertheless, HPS light bulbs degrade slightly slower than metal halide lights. They typically require replacement after 12-14 months of continuous use.

Conclusion

Now that you know everything about HPS grow lights, it is much easier to start growing with them. If you are serious about growing marijuana, these lights will give you ease of use and the best yields. By the way, you are likely to have more enjoyable growing experience as well.

The bottom line is that high pressure sodium grow lights offer high-powered lighting with a spectrum output that’s ideal for cannabis plants. The biggest downside of these lights is a high initial investment as well as the heat generated. That’s something you must take into account when picking HPS light for your grow.

Of course, you need to choose the proper size and wattage according to your growing area. When combined with appropriate MH lights and ballasts, the success is guaranteed at the end of the growing cycle. That’s why HPS light is a logical choice for most growers. Just make sure to choose the best HPS grow lights and you will get the best results.

Next Step: Purchase Marijuana seeds

Now you have purchased your first growing light and the only thing missing is marijuana seeds that you can purchase from one of the cannabis seed banks.

If you are completely new to indoor growing visit home page and read The Beginners Guide on How to Grow Weed at Home in 10 Easy Steps.

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