The LED Buyer’s Worksheet is here! We’re tired of seeing our fellow growers get overcharged or straight up ripped-off by evil, slimy LED manufacturers. The LED growlight market is overflowing with false claims, fake reviews from corporate shills, scumbags and charlatans. As an LED newbie, how can you even tell the bullshit from the straight dope?
This simple, single-page, fill-in-the-blank worksheet cuts through all the hype and false-advertising in 5 minutes flat. We asked ourselves, what does a growlight actually do? It’s pretty simple, really. A growlight consumes a certain amount of electricity. It produces a certain amount of heat, and a certain amount of light. That light is a certain color. You get the growlight for a certain price. That’s it!
With 5 simple questions you can get 99% of the picture on any LED growlight. This worksheet puts the power back in your hands to evaluate and compare any fixture, and to make an informed decision as a customer. The 5 questions are fundamental and vitally important. If the manufacturer doesn’t give you immediate, straightforward answers to all 5 questions then they’re hiding something. Don’t buy their light! We’re not saying you won’t grow anything with a shitty, overpriced growlight. We’re saying there are better growlights available for a much lower price.
The worksheet includes a basic explanation for each of the 5 questions, as well as examples of the type of numbers you’re looking for in a quality fixture. Knowledge is power. ARRR!!!
Question 1. What is the wattage consumed at the wall at full power?
Answer 1. _____________W
Question 2. What is the cost in Dollars per Watt?
(Fixture Price divided by Answer 1)
Answer 2. _____________$/W
Question 3. What is the efficiency in micromoles per joule (umol/J) at full power?
Answer 3. _____________umol/J
Question 4. What is the operating temperature (Fahrenheit) of the heatsink at full power? (78F ambient room temperature)
Answer 4. _____________F
4B. ACTIVE-COOLED or PASSIVE-COOLED?
Question 5. What is the color temperature on the Kelvin Scale?
Answer 5. _____________K
LED BUYER'S WORKSHEET BREAKDOWN
Question 1. You need to be very specific about this. Wattage drawn at the wall at full power is what you want to know. It doesn't matter if the name says LED5000. If it draws 400 Watts at the wall then it's really an LED400.
Question 2. Divide the cost of the fixture by the wattage (Cost-of-Fixture/Wattage) and you get dollars per watt, $/W.
Using dollars per watt allows us to compare the price of every LED fixture, no matter what its size or wattage is.
For example, The Cannon is a 240W fixture, and with your 10% off coupon code the price is $315.
So $315/240W = $1.31 per watt for a single Cannon with the 10% off coupon code: ARRR! )
You can get a top of the line fixture with super-high efficiency and cool controls/features for $2-$2.25 per watt. You can DIY or get a Cannon for $1.25-$1.50 per watt.
Low End (DIY, The Cannon) = $1.25 to $1.50 per watt
High End (Top shelf board/strip fixtures) = $2-$2.25 per watt
Question 3. Be specific about the units here, you need the umol/J (pronounced micro-moles per jewel). The umol/J just means light per watt. It's a way to measure the efficiency.
You don't even need to know what it means, just know that if you're paying top-shelf prices ($2 per watt or more) you should be up around the top of the scale at 2.3-2.4. Anything below 1.7umol/J is a bad fixture, save the money and get a 1000W DE HPS.
Brand New Double Ended 1000 Watt HPS = 1.7umol/J
The Cannon = 2.0umol/J
High-End LED Pucks/Boards = 2.3-2.4umol/J
Question 4. The cooler the LED the more efficently it runs, so a cool heatsink is very important! A high-quality fixture should stay at or below 135F.
The Cannon = 120F passively
50 Watt CXB3590 on a 140mm pin heatsink = 95F passively
75 Watt Vero29 on a 140mm pin heatsink = 135F passively
Active cooling means you use fans, passive cooling means you don't. If you want to keep the noise down and save wattage, get a passively cooled fixture.
Question 5. This is a very basic rundown. For full spectrum LED's, the ideal range is from 3000K (on the red/flower end) to 5000K (on the blue/veg end). 3500K is great for full cycle growth. The Cannon comes in 3500K. Full credit to Growmau5 for showing us the way on this.
An LED will cost the same for the manufacturer no matter what color it is, so spectrum shouldn't have much effect on the price.
Plant responses to spectrum are very strain specific so there is no "magic spectrum". Mixing 3000K, 3500K, and 5000K will give you all the color and all the control you need.
Supplementing 730nm Far Red is the most notable exception here. The results justify the expense, I've done the experiments myself. You can supplement Far Red over a 4' x 4' area for about $50-$100.