Tag Archives: grow light

The Fridgegrow – closed loop growing with co2 support

Weed in a fridge

Flowering cannabis in a fridge
Cannabis that was grown in a fridge using the fridge grow

So when people think about starting to grow weed, they usually look at it from the beneficial side: It would cost less than the shady park vendor or the dispensary in nearly every case, especially when quality is taken into account. The overall quality is more controllable. Plus: In a world with PGRs, terpene spray, brix or artifical cannabinoids its still recommended by me to rather grow at home, than buying stuff simply because the packaging looks shiny.

The fridgegrow controller tries to fill a gap in the homegrow segment. Its not a fullblown all-in-one closet where you have little to no options in terms of light or nutrition, but its also not a tent, where you usually have to deal with environmental values as they come. When the door to the fridge is closed, its not possible to exchange air or even water from inside the fridge. (disclaimer: this is only half-true, but for simplicity we will assume this for that article.) You will have to bring some ingenuity into the operation!

The fridgegrow setup uses a few key elements to keep the environmental values in check:

The fridge

A fridge is able to lower the temperature inside its volume, without exchanging air inside the fridge. Lowering the temperature lowers the possible maximum of moisture the air can hold, water will condense on the cold backwall of the fridge and trickle down…
The fridges total power has to “work” against the grow lights total power, and therefore should be able to “outfreeze” the heat.
The fridge is not included in the system. I recommend to buy a beverage fridge for commercial usage with a closed front. You want to keep the light out. Make sure, that the fridge has as much power as you can get. Its easier to hold the values this way. Heres a fridge from amazon with a clear front, that has to be masked first.

A small heating element

A heater is able to work against the fridge to keep the relative humidity up. In a perfectly dialed in fridgegrow setup the heater will almost never run during the light-on phases, because light and fridge should cancel each other out AND holding onto certain humidity levels while doing so. This is also dependend on the total amount of water inside the fridge chamber.

The perfect light – crescience modular fluXengine LED built

There is no reasoning here for anything else than a high efficient LED setup. No asian amazon light or HPS light will be acceptable if your plan is to grow cannabis in here. Make sure you are able to remove the driver and try to place it outside the fridge. One thing I love about that built is, that I get to chose the light, and its not prebuilt in here!

LED grow light and flowering cannabis in a fridge
Crescience DIY LED setup -3x fluXengine board-style repping the Samsung LM301B chips aswell as a Meanwell – ELG-150-24A

For my fridge I have chosen a modular LED solution by Crescience. Crescience is known for their modularity and compatibilty to standardsized aluminium-framing. Its super-easy to build and you can actually achieve tailored photon-outputs for every system ever.
I am running 3 of their fluxEngines (link goes to the updated lm301h version) powered by a Meanwell ELG-150-24-A Driver.

Some thoughts about the fridge-light-interaction

The principle of continuity says: What goes in has to come out. This is true for everything that has a flow to it. In the case of the fridge one puts energy as heat into the system via the grow light and the heating element. The vapor-compression element on the back of the fridge is able to get heat out of the system and will transport it away through the heatpipes on the back of the fridge. Thats also the reason a fridge is hot in the back and cold inside. Our limiting factor for our light is the fridges compressor efficiency. If our fridge cant transport the heat away through its compressor the inside of the fridge will heat up endlessly, which will result in darkness since the controller will always try to save the plants, no matter if its “daytime” or “nighttime”. This means we need the most efficient and cool running light setup in here. A commercial beverage fridge for business will have a power draw between 90 and 150W from the wall. The light you use should draw a bit less than that.

Air circulation

Small fans directed at the back of the fridge are also an important element in this setup. It keeps the watercycle running smooth and steady. I have chosen Arctic 120mm PC-Fans . I connected them via a 4-way 3-pin fan-connector in parallel and a 12V/2A powersupply. If you are not sure about that, ask an electrician how to wire it.

fans in front of a fridge grow
Arctic PC-Coolers keep the air circulation going in the fridgegrow.

vertical nets or other vertical scrog systems

Keeps your growth in check! I had a few leafs touching the backwall of the fridge keeping the water from dripping down. This results in considerable pieces of ice in there, although its almost 30°C while the lights are on! Ice is bad. It binds water and takes it out of the waterloop.
I gave my plants only 4 glasses of water – in 67 days of growing. And this is a problem.

Scrog in a fridge
Basket-ScrOG system – the grow-space is very limited, so you have to expose as much buds as possible to direct light.

Feeding plants in a closed loop system

While a small windowsill plant doesnt need much to stay green and vital, cannabis under a blasting sun-replacement will transpire significantly more and will therefore have a much increased need of moisture. The trick is to catch the condensing droplets from the back of fridge and guide them back into the pots. Even if youre not able to do that perfectly, the water will still stay in the system, because of the fridges isolation. All you need to do is to close the small hole in the lower back of the fridge, where drops usually get vaporized through the compressor on the back. We dont want that, so we close the loop with a sheet of metal, guiding it back into the pots. This also has disadvantages: Im used to give diluted water-nutrition solution to my plants. Bio Bizz usually is diluted in a way that about 1-5ml of nutritional concentrate gets mixed with one liter of water. This is of course only true for system where the soil can dry out a bit and this wont happen in a fridge setup. You have to put in higher concentration (same amount of nutrition but on a glass of water) or you go for solid nutrition like greenhouse feeding or pre-grow formulas like Biotabs Organics.

I hold my plants in 3 gal smart-pots. Pathological amounts of greenhouse bio bloom and some biobizz was given, but i wasnt really able to conquer the ramping deficiencies my plants developed.

nutrient defincency on cannabis plant in fridge
Leaf discoloration and washed out leaf-tips: this plant was craving for nutrition.

Controlling CO2 – hacking sodamax/sodastream bottles

This is the first setup I was able to make use of extra CO2 inside a grow room. You first need to buy a CO2 bottle, that gets usually used for gassing up beverages mixed together in the kitchen. This bottle is under a standard pressure of about 6 Bar. The first connection has to go to a pressure-bottle adaptor. This adaptor is then connected to a pressure-reducer unit. The reason for that is the next element: its the actual CO2 valve that lets CO2 flow into the system: The CO2-magnet-valve that can be controlled electrical by the fridge-grow controller.

pressure limiter system
CO2 pressure-reducer: left you can see that the bottle-pressure is below 1BAR, so it will have to be replaced soon! On the left is the pressure measured, that lies between the magnetic-valve and the pressure-reducer: theres still CO2 available! But a second bottle would come in handy…

The Fridgegrow-Controller

This is the heart of the system. Its basically a mixture between a server (with a UI to check data and setup the environment ) and a controller. In principle the controller is just turning bluetooth-powerplugs on and off whenever temperature, humidity needs to be dialed in, lights to be turned on and off, or to open and close the CO2 valve. The system is pretty much plug and play and can be setup even if youre not really techsavvy.

fridgegrow controller
The fridgegrow-controller . In the back you can see the droplets of water that will eventually flow back into the soil. On the right-hand-side of the controller is the casing for the temperture and humidity sensor.

The controller will react to different parameters that are more or less dependent on each other. It will find a more or less stable cycle dependent on set values and the amount of water in the system.


The fridge reacts to two central reading: humidity and temperature. It will turn ON when ever the current humidity rises above the set value AND the temperature is high enough.
In this case that means that the temperature is at its set level or at max. 2x below the set hysteresis. A hystersis-value is the margin a value can go above or beyond.
So if you setup the fridge to hold a temperature between 24°C and 28°C (Thats 26°C with a hysteresis of 2°C) and relative humidity between 65% and 75% (set 70% with a hysteresis of 5%) the fridge will only start running when the humidity exceeds 75% while the fridge is between 22°C and 26°C.
The fridge will turn off when values below 70% relative humidity are reached or the temp drops below 22°C which is 2x the hysteresis. You can see easily that reaching the right relative humidity is dependent on the amount of water in the system. The fridge will never get below certain values if theres too much water to condensate.

Light control

This one seems easy: It just switches on and off at set-times.
But the system is also inhibitng fail-save measurements to save the plant. And heres the tricky part. The fridge can actually overheat while its trying to find a cycle, and thats a nono for the controller. It will turn of any heatsource that exceeds the global temperature limit. And thats the set-tempreature plus 2x the set-hysteresis. So in a running system with a 26°C ± 2°C the light will go out when ever the system breaks the 30°C limit to save the plants.
This can actually happen when theres not enough water around to keep humidity high: the heater will run longer to increase the amount of water in the air and will hit the temp-limit before the humidity levels can be reached. This will perodically lead to on/off cycles of the lights! So be aware of your cycles!

CO2 and Heating

CO2 is kind of entangled from the rest. The gas wont interfere with temperature and humidity and will be dialed in by the controller according to the set value and hysteresis.
The heater is your last bastion to figure out your values/moisture levels in the system. If the controller thinks, that a the heater needs to run WHILE the lights are on you have one of two problems:You need less water in the system!

The heater only reacts to temperature, so it will only go on, while the temperature drops too low. This can only be the case when the fridge runs too long against the light, trying to reduce the humidity. If you can dial up the light to create more evaporation the fridge will have a harder time reducing the temps, keeping the heater off.
If theres no use to it, and the humidity levels wont fall of with a constantly running fridge and a constantly running light, you have too much water in the system, so try to remove some. But this is basically the equilibium you want to achive: Running heater only when the lights are off, trying to get a stable water-humidity-temp equilibrium going.

The fridgegrow-app

One last word about the fridgegrow-app. To set everything up you need to be connected to the controller via the app or the controllers local webiste. If you dont connect the controller to your local wifi (which i recommend for safety concerns) you have to use the internal wifi from the controller. The controller guides you through the first setup of the remote-power plugs and is pretty easy to use with a standard UI and graphs of the sensor-data. Perfect for a nerd-grower like I am! In the graphic below you can see that i turned on three graphs, temp, hum and CO2. In the graphic you can see the exact moment when I opened the fridge at 19:15 or 7:15pm. the humidity and CO2 drops significantly as I pulled everything out of it, when I opened the door. The CO2 controller will turn on immediatly while you can also see the heating element tries to work against the fridge to keep the temp low.

screenshot of fridgegrow app
View through the fridgegrow app – setup your controller, check your values – remotely

Wrap-up: Should you buy a fridge grow?

For the beginners: Yes, its possible to just watch and learn with this system. Its really an accomplishment and a good amount of work to have it running stable for the first time, but you will be given a system were you have full control of every aspect of a run, while still be able to hold smell and noise in place.

Its for the nerd who grew weed in the past, but maybe dont want to have the whole fan/tent etc. infrastructure in his family home anymore. Maybe you want to get most of a limited space? This system got you definetly covered. I will try to harvest 100g dry regurlary out of there, and this should be enought to supply a single consumer out there and I am convinced that this system is working since I got my first 60g of Humboldt Seeds OGKZ out of there and it was a more than decent smoking experience. Welcome to the 21 century growers!

DIY 130 W LED light Feat. The crescience FLUxEngine

Video with build instructions

This article will cover how to build a solderless LED light thats scalable and very easy to set up. Check out why LEDs are superior.

The build shown here is beginner friendly. You dont have to drill into metal and the boards do not need active or passive cooling, since the framing will be sufficient to do that. If youre more into COBs, check out my 310W COB growlight guide!

This article will cover how to build a solderless LED light thats scalable and very easy to set up. Read more about how LEDs are superior.

Disclaimer: This piece of electronic is a potential fire hazard and should only be put together by electricians or persons with similar know-how. Please refrain from putting in self-made electronics into the wallplug. Dont die!


For this build you can either buy the whole kit from the LED builders website, or you look for a bunch of groove profiles from metal dealer thats suitable for you. Mind that I cant give an amazon link for that, since the orders are most likely to be custom made.

Groove Profile – use these, so you dont have to drill into metal!

I used 30 cm and 38 cm long profiles with a 4cmx4cm crosssection, so you can build a square-shape out of it.

You also need a bunch of metal sliders. Make sure, that the sliders fit the profiles.

Metal sliders that are needed as holes for the screws.

Every slider needs a fitting screw aswell. To connect the framepieces You will also need some angles. There has to be one on the side where you will buy the framing that fits the profile. It should look somewhat like that:

Angle connector for the frame.

For this particular build I used 4 FLUXengines to achieve a total power of 130 W for the 2×2 tent its used in. Be aware, that these boards might require screws with a smaller head, so you dont drill onto the LED modules.

FLUXengine with the power connector in the front and the Samsung lm301b chips on board.

The ELG-150-24A driver is the connection between the wallplug and the boards. You will need one of these. The boards are connected in parallel.

The driver!

You will also need about 50 cm to 1 m of single core copper cables to connect every board with the driver. I suggest you buy two different colors: one for plus, and one for minus. The cross-section of the wire should be between 0.14 mm² and 0.5 mm². Mind that once you used 0.5mm² cables on the connectors, you will not be able to switcht to the smaller ones.

Single core copper cables are easy to clamp!

For further connections and cable collection you will also need to buy WAGO clamps. Two 5-way clamps to connect all the boards in parallel to the driver, and three 2-ways to connect the driver to plug cable for the wall.

Wago Clamps for cable connection.

Last but not least its important to hang the lights from the top of the tent. Get four hook screws in order to do that.

Use these to hang your light!

Take some measurements first

Lay down your frames in front of you and put the boards on top in a symmetrical way. After that you estimate the cable lengths and cut them. Strip the isolation and connect the cables color-coded to + and to the boards and guide them throught the aluminum profiles. Its better to take longer cut here, hust to be save.

After that you take your metal sliders and also guide them through the profiles. You can now screw the boards tightly to the to the frames, and the framepieces to each other. Before you screw together the frame pieces, make sure to have all sliders in the back installed aswell. You wont be able to access the shorter parts anymore or you have to unscrew everything…

Connecting the cables

The schematic shows how its done. Collect all minus and plus cables together and put them into a 5-way WAGO clamp each. The voltage delivered by the driver stays constant while the current gets forced to a maximum output of about 6.3 A.

All cables are connected, the light is hanging safely – time to grow!

Testing and mounting

Four Crescience FLUXengine modules haning in the tent

When everything is connected nice and tight, you can now plug it in and look if it runs. Dont look directly into the light.

Done! This light should draw around 130 W at the wall and is able to light up a 60cm x 60cm grow tent (2’x2′).

Scale up!

The four modules can also be connected to a bigger drivers. Each module is able to put out 60W of light, so if you have the ability to hold down temps, you can also use ELG 240-42 running at 5710 mA to reach about 230 W with this setup. Mind that these chips run hotter and less efficient in this configuration, but will still crush any blurple or HPS lights in comparison.

DIY 310 W COB Growlight for under $350

render picture of diy grow light
SketchUp Render of the DIY COB Light

In this guide I will describe you in all detail what you need and how to manufacture a COB growlight using state of the art LED technology. 

This is instruction is perfect for growareas of 6 ft² – 9 ft² hanging at a minimum height of 45cm. 
I will also assume that you do not want to use an external potentiometer to dim the light. The light is dimmable through the driver directly.

Disclaimer: This guide is an example for one of the most efficient ways to distribute grow light in a 80cm x 80cm grow tent. If your tent has different measurements it is on you to figure out what is best for your setup. This article is more of an inspiration.

Another note: I am not an electrician. If you are not sure about your build please let a friend look through everything. Don’t die! 🙂

Item list

Aluminium L-profile620
Aluminium flat profile16
Screw tap1amazon15
Norm screw set1amazon19
COB Modules4digikey80
MeanWell HLH-320H-2100A1100
Arctic Processor Cooler4amazon56
Thermal glue1amazon8,5
4-way 4-pole Y-splitter1amazon9
12 V / 1A Power plug 1amazon9
Wago clamps1amazon7

Aluminium Profiles

This will be the framing of your light. You will need 7 pieces of aluminium:

top view render of DIY grow light
Light Framing – Red: L-Profiles, Green: cuboid
  • 6 x 515 mm long L-profiles (measurements below)
  • 1 x 515 mm long cubiod (50 mm x 3 mm)
measurements of the L profile
Measurement of the L-profile

The COB Modules: Bridgelux Vero 29 SE 3500K

picture of COB module

This is your work horse. Four of these lights are enough to light up a 3×3 grow area. The BXRC-35E10K0-D-73-SE is able to put out 147 lm/W with a nice 3500k spectrum (warm white).


  • Can I use other COBs aswell? Yes, but make sure the driver you choose fits your setup!
  • Why is this COB better than others? To compare two COBs you first look at the spectrum. This COB has a 3500 K warm white spectrum. After that you compare the effiency. Cheap COBs from amazon likely use COBs that do not reach the output levels of this light at the same power region. With this one you will only need four modules to reach 310W at this efficiency level. 

The Driver: Meanwell HLG-320H-C2100A

This is the heart of your light. The driver will power your COBs. Read more about drivers here. 
This driver is a highly efficient device which will provide you with a constant current of 2100 ma and a voltage range of 76 VDC to 152 VDC.

Thats fitting for the setup! The COBs need a voltage of 36.6 V. We got four of them and connect them in series, resulting in a total voltage of 146.4V .

Wiring schematic for a series connection

To get the same result while wiring everything in parallel you will need a driver that puts out 8.4 A and 36.6 V constant voltage.

Cooling: The Arctic Alpine 64 Plus

This CPU cooler is quiet, can dissipate up to 100 W of thermal energy and is really cheap! It is also possible to use pre drilled passive heatsinks, but these cost at least $30 each.
Disadvantage of active cooling: It can fail!


Disclaimer: I wont provide exact measurments. Just make sure everything is perpenticular and has some kind of symmetry to it.


First use your screw taps to build the framing. Drill holes at the the marked spots and use your screws to hold everything together. Use one of the coolers to check out the right distance between the two profiles on top and bottom, so the coolers can just be put on top of it.
Remember, that you might need some more holes for the hanging.

Attaching the driver to the middle piece and build the frame

Make sure to screw the driver very tightly to the middle piece, exactly in the middle so everything hangs in an even plane in the end. (no tilt)

example for the frame hanging
My solution to hang the light. 

After that you screw the L profiles and the middle piece with the driver togehter. Work as exact as it gets. If done right, the drivers should fit into the gaps.

Framing of the DIY COB
This was my first framing. Its not perfect, but good enough 🙂

Attach the COBs to the coolers

In the case of the Arctic cooler im recommending, there will be a layer of heatconducting paste on it. You have to remove it, before you attach the COB.

Back of arctic alpine cooler
Remove the layer of thermalpaste first

To remove the thermal paste you need to use a special alcohol solution. This one here is sufficient.

heatpaste removal
Use this or an equivalent solution to remove the thermal paste.

After that you can apply the backside of the COB with a little amount of thermal glue. 


Heat paste on COB module
This is a good amount of thermal glue. Let it spread by pressing it on the cooler.

You do not need to spread the thermal glue manually. Just press it on the cooler and let it distribute by pressure.

Wiring and testing the lights

Wago clamps
Use the Wago clamps to connect cables.

Place the COBs attached to the cooler on the framing to determine the amount of cable you need. After that you can start cutting the right amount of cable and wire it to the COBs. Please watch this video if you are not sure how to wire a COB.  Remeber: You use serial wiring.
You now have to attach the input cable to the driver. Just cut open a cold device cable. Make sure you work according to the color coding of the wires. If you fuck up here it can be dangerous! Use the Wago clamps to connect everything.
If you think you have done everything right please DOUBLE CHECK everything.

Attach this to your driver. This is an EU cable!

You can now test the COBs for 5 seconds max. This is important, because the active cooling is not connected yet. Cover your eyes, this is going to be bright! (Im serious here!) 

Power up the cooling

Now that the light works, the last step is to connect the cooling to the power. This is why you have to buy a 4-Way Y-connector. This is used to wire all the fans on the coolers together. Then you just connect the remaining wire to a sufficient power source (12 V, 1 A) and you are done. The cable from the Y-connector has four wires and are color coded as shown here. You only need 12VDC and GND to run the fans. If you are clever you make use of the PWM cable as well to lower the rotation speed if needed.

COB light in a growtent
The DIY COB Light in action!

Have fun growing!

How to evaluate growlights- Part One: Phlizon 600W LED

Disclaimer: Blue/Purple grow “lights get the job done”. But do not expect more than that.

This article is a rant.
Its subjective, but backed with sources, experience and knowledge from over four years of growing with alleged top notch technology.

People are pretty simple if it comes to marketing. Everyone wants to buy the best valued components for the best price to get going. If you ever build your own PC or a drone you will know what im talking about. 
Creating a grow setup was a simple task ten to twenty years ago. You just had to go to one of these grow shops, where you talked with a clerk to get the best out of your budget for your operation. You got a tent, a HPS light, soil, nutes, seeds and some ventilation. Online and offline sources were limited to a few books the old masters wrote.

With spreding legalisation many companies jumped on the grow train trying to advertise their products to you. And i have to admit: They are good at it!

Google results for "grow light"
Google result of  “grow light” … That says it all.

Just google “grow light” and you are flooded with the infamous blue/purple spectra of common grow lights you find on amazon or alibaba. But a great search engine optimization does not equal the quality of the product.

False advertisement

To be honest: There is nothing wrong with running these lights. They are getting the job done. They will not get you near the results you always see on the famous pictures circulating on the internet. The lights are often praised with heavily exaggerated numbers. I will discuss the most bought LED grow lights from amazon.com and show you whats wrong with them.

Critical cannabis in flower
Get back to me, if you manage to do this with a single Phlizon 600 W. I did this with a 310 W light. So yours should be at least in the ballpark of my result. 😉

Example One: Phlizon 600W LED

Phlizon light from amazon
Phlizon 600W LED light. The hangers and hygrometer are actually useful. Pic from amazon.com

NO REFLECTOR NO DANGER- Many others’ grow lights are used led spotlight reflector to make the light look beautiful, but we don’t use it because the led reflector is not heat-resistant. If a short circuit occurs,reflector at 80℃ is easy to melt and fire. we do not use the reflector, we can not give up the safety beause of beauty.

Amazon Description

Reflectors are a thing of beauty huh?
Phlizon claims, that reflectors are useless and just melt, if there is a short circuit.
Do they assume their light will short curcuit at one point?
LEDs are emitting light in all directions. It actually enhances the optical properties of a light if you use reflectors. They just ditch them, because they think its just a cosmetic element. You actually need them to focus the light more in the direction of the canopy.

FULL SPECTRUM- We did lots of experimentation to ensure that this full spectrum design promotes plant growth. It includes universal Blue Red IR UV and white light provide everything plant desire in the natural sunlight. The expensive IR UV led promote plants to defense mechanisms, blue and red led is essential light for plant growth.

Amazon Description

Okay! Thats bold. The spectrum is one of the least “white” ones you could imagine. Its mainly blue and red. The McCree curve, where you can see, what intensity distribution your light should have is vastly different from Phlizons “white” light. White light is created if the spectrum contains of every wavelengths in equal parts. Its fine to build an only red-blue light, but do not call it white.

McCree Curve vs the phlizon spectrum
The McCree Curve behind the “full spectrum” of the Phlizon 600W spectrum. You get an idea whats missing here.

DOUBLE SWITCH- Veg and Bloom button have different function. Veg switch: It’s blue led and white led. For seeding or young vegetative growth,you can use Veg switch only. Bloom switch: It’s red led and white led.for flowering/blooming,you can use both Veg and Bloom switches. View Angle of LEDs: 90°and 120°

Amazon Description

Thats actually cool to save money on energy. I really doubt that your plants do well under one of these lights switched to veg, but useful nontheless. Good LED COB or Quantum Board system got a dimmer as well to do save energy.

COMPARE TO HPS/MH- The 600W LED grow light can replace traditional 400 watt HPS/MH while consuming only 108 watts! More effective coverage area than any reflector series lights. perfect for a 2x2ft growing area at 24″ height. The difference of us is that we use double cooling fans. Can most extend the light life.

Amazon Description

There is so much bullshit in here…
WHY would you name it a 600W LED if its an ACTUAL 108 Watt LED claiming it will replace a 400 Watt HPS
It will not even come close to a 400 Watt HPS output. The only honest fact in there is, that this light is perfect for a 2 x 2 environment. No grower with the right mind would setup a REAL 600 Watt light in that, nor a 400 W hps. 
What other purpose is there but to confuse the customer?

More confusing info

Screenshot of lamp info
What color is 600 W? The wattage is 108 Watt, not 600! From amazon.com

The made up 600 W are pulled entirely through the hole descripton. You can actually light up an area of 1.44 m² with a high quality 600 Watt LED light. This area is about 4x bigger than the 2′ x 2′ space advertised.

PPFD values from Phlizon amazon lamp
PPFD of 260 at 24″ distance is  about 1/4 of the optimal value. From amazon.com

They also claim that a hanging distance of about 24″ (61 cm) is the perfect height. I will not believe them any further but a PPFD value of 260 is way below the 700-1000 a high quality COB/Quantum Board light will deliver.

Conclusion: Phlizon 600 W

  • No, it is nowhere near a 600 W LED light. It is a 108 W low quality LED. You can replace your 100 Watt HPS with that, and will be happy, that this abomination will run a bit cooler.
  • No, the spectrum is not the perfect fit for your flowers. It is mass produced lowball asian LED that get put into mass produced low quality LED arrays.
  • You need actually 6(!) of these to light up a 5′ x 5′ tent. Thats about the size a high quality LED with 600 actual Watt could light up. That will cost you about $540. Buy a real light instead.

Do not buy this light if you expect a high yield, high quality harvest.

Buy this light if you just want to take a look into the hobby. But you might want to upgrade as soon as possible….

Grow Lights – Theory of Light

In this chapter you will learn about the different aspects of light in gardening. It clears up all the different keywords and hopefully all technical terms that occur when talking about light.

Definition of Light

“Light” is actually defined as a thin part of the electromagnetic spectrum. Exactly the one we can see with our human eyes. 

Light can be divided into parts called photons, which act in theory as light particles. According to physics you can treat light as a particle and a wave simultaneously. We will need both ways in this chapter!

Short wavelenghts means high frequency. Higher frequency correlates to higher energy per light particle. Long radio waves, which can expand to several meters in wavelength have a very low energy per photon.

Electromagnetic Spectrum with the visible part in the middle. From: Wikipedia

Defining a light source

If you want to learn about lightsources such as Light Emitting Diodes (LEDs), High-Pressure Sodium lamps (HPS), Compact Fluorescent lamp (CFL) or Ceramic Discharge Metal Halide (CMH) you will not only have to look at the specs each of these lamps have, you also have to look at the theory on which the light is created. Every single light source used for growing has its advantages and disadvantages.

All light sources used for growing work with a the same rough principle:

Turn electrical energy (input) into light (output)

The devil is in the details. As always. What I will describe now is awful lot to learn and difficult to have alook through. But its worth the reading, and after this you will be more able to decide wether a light is “good” or “bad” for your cause.

What light does a plant need?

Plants have two main sources of energy: The root environment (soil, water, aeroponics, nutrition…) and the light that shines on its leafs. The process in which the leafs turn light energy to “food” is called photosynthesis.

Not every light that a plant is exposed to, is usable to do photosynthesis. A human eye can basically see every color between 390 nm and 700 nm, but is blind for colors that have lower wavelengths (ultra-violet) or higher ones (infrared). Humans are most sensitive for the color green. As opposed to plants. Keep that in mind when you get to the unit section

Plants have a similar spectrum, but see actualy green light the least. Thats obvious, since leafs are commonly green, so they reflect the green parts of the spectrum. The three ingredients in a leaf that are responsible for the reaction are Chlorophyll-a and Chlorophyll-b as well as Carotenoids.

Bottom: Spectrum of photosynthesis rate –  There is a big dip in the middle.

Top: If you build the sum of the three top spectra, and take into account, that the different parts that are responsible for the photosynthesis are available in unequally you get the lower spectrum. Chlorophyll-a is obviously the main driver for the process.

If you look at the lower spectrum in the picture above you can get a sense of what kind light a plant likes to receive: two broad bands of light between 400 nm and 500 nm and between 650 nm and 700 nm. One is in a blueish region, whilst the other is rather red. 

The Relative Quantum Efficiency

The three molecules (molecule groups) Chlorophyll-a ,Chlorophyll-b and Carotenoids are not the only driving factor of photosynthesis. In of the most cited articels from K.J. McCree (1972) he measured how the plants react to light of different wavelengths. He found, that the area around the green light (550 nm) is actually well used by the plants. Not as good as blue or red light, but up to significant margin! So green light is not inherently bad for plant growths.

Mc Cree curve showing the photosynthetic efficiency of green leaf material. The experiment is from 1972, so it might be time to reevaluate. In this graphic we see the impact of  red and blue lights in growing, but you can also imagine that green light is also important.

Measuring light – A jungle of units

Now that we have the favourite colors of a plants light dinner, we need to figure out, how much they need! This is determined by the amount of light a source can emit. This amount can be described with various units of measurement. Some of them make sense for growing (PAR, PPFD), others don’t (lm, lux), and the rest is not normalized and/or very subjective in a way that it is depending on the experimental setup one uses to measure it.(also PAR/PPFD).

The following part will enlighten you about the different units of measurements scientist and light distributors characterize light.
Note: I tried to sort the units in order if importance, starting with the most important one.

PPF and PPFD – Photosynthetic Flux
Photosynthetic Photon Flux Density

Lets dive right into things. So photosynthesis is a quantum process. Just think about it this way: A leaf is plastered with billions of little molecule-machines trying to catch light particles in the exact right energy range. The more machines are hit per timeframe the better. So PPFD counts the amount of photons (µmol) that hit a certain area (m²) in our timeframe (s). This results in the unit of measurement:  [PPFD] = µmol/m²/s

A PPFD value of 900-1000 µmol/m²/s is needed to saturate a canopy area of plants if you use a warm white spectrum!  How to get an even canopy using LST!

PPF on the other hand only counts the Photons emitted by a light source, but does not take into account any absorption effects. So if a photon is emitted through a source and runs right into a the case of the light, its counted towards PPF but not PPFD. [PPF] = µmol/s

The counted Photons also have to be from a certain spectral area between 400 nm and 700 nm. Everything else is not counted!

Two different lights: Blue has a smaller wavelength and can transport more energy per photon than the longer red. Source: http://www.shorstmeyer.com/wxfaqs/Blue_Sky/bluesky4.html

Example 1: Lets say we have two lights emitting 100 photons a second on a normalized area. One is blue, one is red. The blue photons contain more energy. The PAR value would be higher for the blue light. The PPFD value would be actually dead even because both lights emit the same amount of photons in the active range.
So which light is “better”?
Answer: The red one for flowering, the blue one for vegetative growth. This is also the reason “common grow lights” give you both parts of the spectrum which results in a pink look of the lights. (blurple if you want…).

Cannabis plant under a grow light with a blue/purple spectrum
Cannabis plant under a grow light with a blue/purple spectrum. Source: homegrow-pro.com

Example 2: We add a green light to the show with an output wavelength of 555 nm monochromatic light. Its PAR values would be better than the red light, but worse than the blue ones. PPFD would be dead even again. Do we take the green one now?
Answer: No! A green light is not effective to grow cannabis. The plants will not be able to do photosynthesis with green light, as effective as with the use of fullspectrum systems, because they simply reflect alot of it.

Grower inspects his plants with a green headlight.. Source

Conclusion: When reading about PPFD values in the description of your light, always take a look at the spectrum as well. If the light “wastes” alot of intensity on green wavelength the number is not as useful anymore! If you have a high PPFD value it can mean less if it has mostly a green spectrum.
Its also interesting to look at the light distribution a light creates at certain distances to the source and wether the source created an even output! If there is a disproportion between PPF and PPFD its often times a lack of optical diffractors that distribute the light uneven to the plants. Take a look at a HPS lamp that creates light in a very narrow area inside its tube. This creates a very uneven distribution on the surface area: Buds on the edge of the light cone will develop more poorly.

PAR – Photosynthetically active radiation

This is easy to figure out: You imagine a perfect black surface and shine a light on it. The hypothetical surface (m²) absorbs the energy at a 100% effectivity which you can measure. Within a certain timeframe we can now measure the power (W) emitted by the light in [PAR] = W/m². The counted photons are again in the 400 nm to 700 nm range.

Here is a subtle difference to the PPFD value we learned about in the last section:

Example : Imagine two light sources. One monochromatic red and one monochromatic blue one. The red one has an output of 200 photons a second with 700 nm in wavelenghts, while the blue one puts out 100 photons with 400 nm. PAR does not care if the plant can use this light, it just takes the values because they are in the range where we observe PAR. So regarding PPFD we learned that the red one should be twice as good as the blue one. But on PAR level both are about even, because the blue light can carry more energy than the red one and PAR only cares about energy over time on a certain surface.

Conclusion: PAR can be at a high value, because it gets pushed through high intesity of blue parts in the spectrum (more blue wavelengths). Always check PAR, PPFD and the spectrum.

Light distribution under a metal-halide light: perpenticular to the source direction the light is most intensive. PAR values might look good, but whats measured at a surface level is also important! 
PPFD takes uneven distribution into account

W – Real Power Draw (Watt)

The Wattage of a lamp is a good ballpark number to start searching for a light source. Its actually the first value I look at, and from there you start to compare lights on the same level!

The power draw from the wall can directly calculated into money that appears on your power bill. So this is often the first thing you want to check. After this, you find out which light converts this money to the best possible PAR/PPFD/spectrum combination.

Many light suppliers tend to market their lamps with this value to its customers. 

Blue/purple lights from various distributors will name their lamps after “artificial HPS equivalent Watts” to trick the customer. You might think that a 600 W LED with the an awesome blue/purple spectrum is the deal of the day. Be aware that these companies hide the true power draw in the description at amazon or eBay. And they are good at it. Don’t get fooled.
If you think you can have 600 W of high quality LED plug-and-play light for 100$ you are WRONG.

Always check for the real power draw.

  • If you’re going for HPS/CMH/Lowball LED light: Calculate with at least 50 W/ft² for decent results.
  • If you are using High-Quality LED Lights (COBs or Quantumboards): Calculate with at least 35 W/ft² for decent results.
This Phlizon is marketed as a 600W LED Grow-light for mind-boggling $89.99. Its actually a 108W shit light, thats not even suitable to light up a 2×2 tent. ONLY BUY THESE LIGHTS IF YOU ARE ON A BUDGET! This scam is actually the “Amazons choice”…….

lm, lm/W – Lumen, Lumen per Watt

Now we’re really deep down the cave. But still: Companies try to catch you with values like this! 

Lumen is one of the least scientific units around, but still has some meaning for interior architects and astronomers. The unit is an abbreviation from the units candela (which literally refers to the output of a burning candle) and the so called luminosity function.

Quote:  “[…]
luminous flux is 
weighted according to a model (a “luminosity function“) of the human eye‘s sensitivity to various wavelengths. ” (Source)

So if you are following you might wanna ask yourself something. 
First remember: The human eye can best distinguish green wavelengths, because it is most sensitive around the 555 nm value. A plant is literally blind in this region.
WHY would you buy a light only because it has awesome lumen values?!

As always: check the spectrum! If the light is mostly green it will have awesome lm values. And perhaps, if its a modern LED, also great lm/W values. But it might not really suitable for growing.


How The Pro chooses a light

When it comes to the decision for the grow lights people always hassle. The market is flooded!

  1. Determine the size of your grow area and find out how many of the sweet Watts you want in there. The unit might not mean much, but you gotta start somewhere! Example: 3×3 tents have 9 ft² of space, so we need about 315 Watts of High Quality Growers Masterrrace LED Awesome Lights, or 450 Watts of Lowball LED / Good-old-fashioned HPS or CMH lights. Make sure your light has a PPFD value of 700-1000 at canopy level, has a full spectrum (warm white) and an efficiency of 120-200 lm/W (remember that you can use this number only for lights with similar spectra).
  2. How is your budget? Great LEDs are expensive, but worth the money. Pre build ones come for $1-$4/W in various forms. So youre looking potentially at $315 – $1260 just for the light. If you want to save money you can choose low-quality LEDs for like $250 that will reach 300 Watt if you buy 2-3 fixtures. Or you just go for a HPS setup for about $150 as a bundle with reflectors and balast. (I wont go into the details here)
  3. Lower your expectations! Great, you just want to take a look into growing and chose the entry level LEDs. Thats totally fine! You can grow awesome weed with these lamps! But if you ever feel you are missing out on something, come back and read about the real LEDs.
  4. Did you really get the HPS?! Thats also fine. They are working for decades and give awesome results. Come back if you think about buying an AC unit and have nightmares about your power bill…
  5. You cant decide between two or more lights? Compare PPFD/PAR/spectrum values at the same Wattage and find your favourite! A light should at least bring the PPFD up to 700 – 1000 in the sweet spot.
Spectrum of a Mars Hydro 300 W light normalized by maximum intensity. The spectrum is good if you just consider the PAR spectrum, but misses out heavily between the red and blue lines if you take the McCree curve into account as well.

LEDs recommended by The Pro

I’m not getting paid for it (yet) but here are some lights i will approve. I saw the results from growers and if you want high yield, dense buds and fast growing weed with low internodial distances buy from them. They also tend to run much cooler than HPS lights…

Timber Grow Lights (US)
Horticulture Lighting Group (US)
Cob Shop (US)
Greenception (EU)
San Light LED (EU)
Rapid LED (US)

Build your own!

Don’t try to buy a good grow light on amazon.com