Last Updated Feb 27, 2022
1. Intro
2.The Doc’s Buying Guide
3. Buying from Alibaba
4. Growing with LED PCB’s
5. LED Flower Density
6 .Horticulture Lighting (HLG) Vs Alibaba
7. LED Board PPFD
8. COB vs Quantum Board (PCB)
9. History of LED Grow Lights
10. Full Spectrum LED vs HPS
Full Spectrum LED Boards (aka quantum boards or printed LED boards) have the highest photon density per dollar making them the best full spectrum grow lights on the market. No fancy box or marketing, just powerful LEDs and a heatsink. There are a variety of LED grow lights on the market but nothing can touch the value, PPFD output and yield of a 3000k LED Board. (See History of LED Grow lights). LED boards make DWC growing much easier due to their low heat output, as compared with HPS bulbs.
Full Spectrum boards are an array of LEDS (e.g. LM301b 0.2 W) that are printed on a circuit board which is affixed to a heatsink and typically powered by a Meanwell Driver (voltage converter). There are no fans so the lights rely on air movement for heat dispersion.
LED Board Printing
They produce an appealing white light that allows you to properly view and enjoy your plants. This is in contrast to the blue/purple LED’s (codenamed “blurple”) that plague amazon.
“blurple” lights that plague Amazon
Visually appealing 3000k Full Spectrum LED board
My preferred seller on Alibaba is Shenzhen Meijiu Lighting Co., Ltd. They have over 8 years of transaction history and have excellent customer service. Many people on Reddit have also had good experience dealing with Shenzhen Kingbrite Electronics Co., Ltd. (5 year transaction history). These suppliers will even laser etch a custom logo on the heat sink at no extra cost. Remember to use the links below to ensure you are dealing with established sellers, there are new sellers that will make fake names (e.g. Meiju vs the real Meijiu).
Atreum lighting recently sent me their awesome ARA-6 fixture to test out. I had always preferred the LED Board style because they were much cheaper than the bar or spider style lights (I am guessing mainly due to shipping costs, as well as the additional hardware.
The reality is that light distribution is way better with these lights. If you can afford the price difference I recommend going with bars over panels.
There is effectively no difference between the LM301B and the LM301H lights sold on Alibaba. Samsung put out a press release about a new line of horticulture branded LEDS (hence the H in LM301H). There are rumours floating around that the LM301H lights have additional anti-sulfurization coatings to make them more moisture resistant for horticulture applications, but Samsung does not even claim this in their own press release.
Regardless Alibaba sellers ran with this and started listing LM301H options at a 10-15% premium. The fact of the matter is that this is a suckers trap, I have had their sales reps confirm they use the same LEDS for both LM301b and LM301H panels. This is why all buy links above are for the standard LM301b.
Epistar, CREE and Samsung are major manufacturers of Light Emitting Diodes. Epistar is made in Taiwan, CREE is an American company and Samsung is South Korean. The majority of lights sold on Alibaba will use Epistar LED’s because they are the most cost effective. Alibaba sellers will claim to sell Samsung LED’s but similar to the LM301B/H I suspect that they use Epistar no matter what. The good news is that Epistar makes high quality LEDs and nobody I know has reported any dead diodes over the 2 or so years that these boards have been reigning supreme.
Alibaba trade assurance protects you as a buyer. It is similar to the trade protection Paypal offers when using eBay. If there are any issues with your order you can request a refund from Alibaba within 30 days of delivery date. Alibaba will mediate the dispute so you don’t even have to deal directly with the seller. That being said I have found Meijiu and Kingbrite have excellent customer service and will often offer to send a replacement unit if you request a refund.
Alibaba lights are shipped globally via air freight which usually takes 5-10 business days. The shipping rates are calculated by weight so combining orders does not typically result in large savings in shipping. Alibaba sellers will air ship LED Boards direct to the United States, Canada, United Kingdom, Australia, Germany, New Zealand, Russia, France, Finland, the Netherlands and many other locations across the globe.
I have flowering footprint recommendations with the lights linked above, but you can also do a watts per square foot calculation if you are working with non typical footprints. This only applies for full spectrum LED PCBs and not older LED’s
Low Range : 25W / Square foot
Money Zone: 30 – 40 W / Square foot*
High End: 50 – 60W / Square foot
*Credit to LED Gardener for coining the money zone.
PCB’s are extremely powerful, even at 50% power. I use flourescent lights in my propagation room because I do not have enough height to run QB’s. Distance from plants should be 5’+
During Veg your goal should be to slowly acclimatize your plants up to 100% power. Start at 4′ above the canopy and slowly lower the board down to 28″ – 36″ above the canopy. During veg light burn will display with the sides of the leaves curling, or what I see most commonly is the leaves taking on a 3D shape.
For flower you can slowly start to bring the board down to 18″ above the canopy. Light burn is easy to spot during flowering as the pistils will look brown and scorched. You may also get LED bleaching though I have never actually seen this myself. I have had the panel within 15″ of the canopy but any closer than that and you are asking for light burn.
The ideal spectrum for flowering Cannabis is 3000k or 3500k. Always get the configuration with the additional red strip (labeled as 660NM on Alibaba). This helps big time for flowering. In the off chance that you are only using your LED boards for vegetative growth go for 4000k
3000k – Dedicated Flowering room
3500k – Flower & Veg
The Meanwell driver typically comes with a built-in dimmer. Use a small Phillips head to adjust the brightness. There is no gauge so you will have to get a feel for it. Go from max to min to get an idea of the range. As of June 2020 all units from Meijiu are being shipped with wired dimmers. Great improvement over the screw control.
Sunglasses are a must. Full Spectrum LED boards are incredibly powerful and will damage your eyes. Don’t play around. Have extra sunglasses for anyone you show the plants to.
If you are growing in a plywood grow box I recommend affixing the driver to the ceiling. With grow tents, the best spot for the driver is typically on top of the heatsink. Make sure you have adequate ventilation if placing on the heatsink. The Meanwell driver should never be too hot to touch.
For grow rooms I like to mount two 2×4’s or 2×3’s about 8″ apart. This allows you to securely affix the Meanwell driver to the ceiling while allowing for air movement all around the driver. Hanging hooks for the lights can easily be screwed into the wood.
Meijiu and Kingbrite have improved the wiring guides they include with their kits but if you have any trouble user Sanez has a detailed wiring guide for the 240W light on the grasscity forums. There is no soldering required, the wire connectors provided are tightened with a screwdriver
LED Gardener is an incredibly useful resource for those that want to build their own LED boards by buying individual parts (i.e. driver, LED Panels, heatsink). He has a number of DIY Guides and a handy driver selector. This is more advanced and requires some electrical experience, be safe.
There is a myth that HPS is required to produce dense nugs. The idea is that HPS lights radiate heat that’s absorbed by cannabis. There is no evidence to support this idea, that is simply not how photosynthesis works.
The thicc nugs above were grown by me under a 240W Full Spectrum LED board. The strain was Wedding Cake and I used slight co2 supplementation from some fermenting beer. It was grown under 12/12 and flowered for 68 days flushing on the last 3 days.
If density is what you are after auto flowers are a good option, since you can run them on 18/6 or even 24 hr lighting through the entire flowering phase.
The LED’s on full spectrum boards are rated to last 100,000 hours and will operate at 80% efficiency after 4 years. The rated life is over 22 years at 12/12 or 11 years running non-stop.
High Pressure Sodium (HPS) lights in comparison are rated for 24,000 hours, meaning you would have to replace bulbs 4x more frequently.
Aside from the manufacturers advertised lifespan, it is important to factor in efficiency drop over time. YouTuber MIGRO released a video on Feb, 5 2020 documenting the results of a year long study of efficiency drop of PCB LEDs (Quantum Boards) and so called COB lights. He found an average efficiency drop of 5% per year. Therefore, it is estimated the lights will reach 80% efficiency after 4 years. This is the recommended time to replace your lights, or add supplemental lighting.
Credit to YouTuber MIGRO for the chart above
Want to start a debate on reddit? Make a post about Quantum Boards and the shills from HLG will be down voting you to oblivion.
As I speculate later in this post Horticulture Lighting Group named themselves HLG to co-incide with the Taiwanese made Meanwell HLG drivers that power all LED boards.
Aside from that HLG is certainly worth mentioning in this post. People on reddit have told me HLG has trademarked the term “Quantum Board” referring to LED PCBs. The company charges what I consider to be an unreasonable markup, which is why I created this guide for those looking to save money by buying direct. In the 100W category I actually recommend buying their version as the markup is not as egregious, and by the time you factor in air freight it makes more sense to buy from Amazon w/ free shipping.
They also drive some innovation in the market. Their new r-spec boards come with a small wire cover. The Alibaba boards at the time of writing this still have exposed wire.
The markup on HLG boards is 150-200%. At the time of writing this the HLG 550 (which is actually just a 480W board) costs $850 USD +$40 flat rate for shipping for a total of $880 USD!
By comparison the Meijiu 480W w/ RED light strip + glass cover costs $310 USD and the Kingbrite 480W comes in at only $250 USD. Factor in shipping and duties and you are looking at approximately half the cost of the Horticulture Lighting Version.
Spider Farmer is a new player in the LED PCB market and their prices are more competitive than HLG. With some users experiencing delays due to Coronavirus these lights look even more attractive
The 3 factors that influence that rate of photosynthesis are CO2, Temperature and Light. The amount of light is measured by PPFD or Photosynthetic Photon Flux Density and expressed as μmol/m2/s. In layman’s terms it the the rate at which photons hit a given area in your canopy over time.
PPFD is more reliable measure than lumens for plant cultivation. This is because lumens only measure visible light and ignore the full spectrum of light required for photosynthesis. Credit to Fluence Bioengineering for the helpful visual below:
LED Gardner has done a lot of great work in measuring PPFD of LED boards. The picture below shows the PPFD dispersion for a 260W QB.
PPFD required for cannabis cultivation is 500-1100 μmol/m2/s with co2 becoming a rate limiting factor at around 600 μmol/m2/s. PPFD can be increased up to 1100 μmol/m2/s with co2 supplementation. For the typical homegrower it is not necessary to measure PPFD. Use your plants as your indicator. Keep the minimum height to 18″ and if you notice any scorched pistils move the light further from the canopy. I have gone up to 900 μmol/m2/s without co2 supplementation and not experienced any scorching. Push your plants to the limit to find what their tolerance is. Credit again to Fluence Bioengineering for the graph below.
COB vs Quantum board is slight misnomer because technically QBs/PCBs are an array of COB’s. In most instances when people refer to COB’s they are typically mean the 50-watt pucks pictured above. I prefer LED Boards over COB’s because they offer more even light distribution and require less vertical distance from the canopy, which can be at a premium in microgrows. With my COB’s I find I have to have the light at least 30″ from the canopy or I experience light burn and pistil scorching. With LED Boards I can get my mounting height down to 18″ from the canopy.
LED Boards are also much cheaper per watt compared to COB’s. At the time of writing this a 240-Watt LED Board could be had for just slightly more than 100W worth of COB lighting. Printed LED boards are the clear winner in this comparison.
Sometimes the Meijiu or Kingbrite rep will include a strange seductive pic with the order. Be careful with who you let open this package XD
The first LED grow lights were Blue/Purple LED grow lights you see all over Amazon. They are commonly sold under Mars Hydro, Viparspectra, and Philzon branding including many other. Internal components are the same, you can get factories in China to engrave whatever name you want on the box. Just don’t put the Grow Doctor’s name on this obsolete junk.
Surface Mounted Devices (SMD) – SMD’s have only one diode per chip, making them much less efficient than COB LED’s which can have 9 diodes or more per chip. The transition from SMD to COB LED’s is most apparent around 2013-2014 when cell phone flashlights started getting really bright. SMD’s have the advantage of being able to change color at the expense of being less efficient
SMD 5050 LED
SMDs are still used for light strips
SMD5050 represents a 5mm wide LED while SMD3528 is a 3.5mm LED. SMD’s are still useful in light strip applications to supplements COB lighting.
The main difference between SMD and COB LED is the number of diodes. Much like advancements in microprocessors, our ability to pack more diodes in a small space led to greater efficiencies at a reduced size.
‘Growmau5’ was the first to start using CREE COB LED’s to grow cannabis. He rose to fame among online grow communities with a series of DIY youtube videos showing yields exceeding 2 grams/watt. With traditional HPS lights, you were a master grower if you could achieve 1 gram/watt.
The growmau5 style involved using massive single COB LED drawing 50-100 watts per chip. The light is spread out from this single point using a 90-degree lens. The lens is mounted to a heatsink which has a small Meanwell driver above it regulating current and providing the required voltage.
COB LED’s are identified by the yellow phosphor coating which turns the blue light white
The issue with these CREE COB’s is higher cost and less effective light dispersion. Some claim that the greater intensity penetrates the canopy further but this theory is not supported by my experience.
Where is Growmau5 now? He partnered with RapidLED and started a line of ChilledLogic LED fixtures. The ‘pucks’ on his new lights resemble mini LED PC Boards. Instead of one large COB LED they have dozens of chips on a round board. It is a nice design which looks clean. They also lack the even light dispersion of a printed LED board. You can see that even Growmau5 himself has moved away from using single high power chips in the 50-100 watt range. The heat with these mega chips is too concentrated and needs to be spread out over a wider surface.
LED PCBs – are the solution to heat issues/light dispersion problems that high power (50-100 watt) chips face. Their advantages are two-fold. PCB’s provide more even light/heat distribution to your canopy. They are also more cost-effective when using the doctors favorite metric: PPFD/$. For example, a 100-watt single chip CREE will run you approx $100 while a 240-Watt PCB Board can be had for $140.
Samsung LM301b – Most common LED on printed circuit boards.
HLG branded printed LED board
Alibaba boards use the same Meanwell HLG driver that Horticulture Lighting uses. The Doc suspects that Horticulture Lighting Group named themselves HLG to coincide with the name of the Taiwanese made Meanwell HLG driver that powers the board, causing confusion in the marketplace.
LED vs HPS is a very common question for new growers. HPS lights have been the standard growing light for decades. In 2020 LED lighting is the better choice in almost all cannabis growing applications. We’ve reached a break-even point where it no longer makes sense to invest in HPS technology despite the slightly lower startup costs. See the History of LED lights for a brief background on how LED’s have evolved over the years. Even governments have gotten wise to this and are replacing HPS street lights with new LEDS.
High-Pressure Sodium (HPS) lights are inefficient when compared to LED. Up to 70% of the power is wasted as heat, you then need to expend more energy to remove this heat from your grow area. There is a direct equivalency between watts and heat, no matter which lighting source you use.
1 W = 3.412 Btu/h
So a 240W LED Board will generate the same amount of heat as a theoretical 240W HPS. The difference is that the quantum board will yield ~2-3x more. Typically, you would need to run a 600W HPS in the same space to approach the same yield. This often leads to overheating issues. Especially with DWC where maintaining cool water temperatures (max 68F) is essential to preventing root rot.
As mentioned above-LED lighting yields on average 2x more at a given wattage. With HPS lighting hitting 1g/watt was considered a milestone.
HPS Yield:
0.25-0.5 g/watt -Average
1.0 g/watt – Expert
LED Yield:
1.0 -1.6 g/watt – Average
2.0+g/watt – Expert
Note that the ‘expert’ values above typically involve the use of co2 supplementation and providing ideal growing conditions for your plants.
Electricity savings in the first grow will cover the negligible higher initial startup cost (approx $30). You can use my electricity calculator to determine your annual electricity costs to compare. I will compare a 600W HPS with a 240W LED board as they should yield approximately the same amount.
600w HPS cost = $130 USD on Amazon (free shipping)
240W LED Board = 100 + 40 Shipping + 30 Duties
240W LED Board = $170 USD (via Alibaba)
As you can see the price difference for equivalent producing HPS and LED lights is only about $30 USD. In Ontario, Canada the cost of electricity (off-peak) is $0.107/kWh.
You save 340 kWh by using an LED Board over an HPS light in the example above. At $0.107 kWh it would take only 2 months of running the lights to reach your break-even point where LED is more economically viable. Over a 1-year period, you would save $164 by running an LED Board over an HPS light at the 240W LED/600W HPS level.
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