LED Grow Lights FAQ
LED Grow Lights Frequently Asked Questions
We have a ton of LED grow light information in our FAQ! Find the answers to your questions below.

FAQ Categories
- Why Buy Black Dog LED?: At the highest level, what makes our lights the best?
- About Black Dog LEDs: Information about our lights.
- Spectrum / Color: Information about the colors / wavelengths of our light.
- Usage: How to use our lights and grow with our lights.
- Electrical: Voltage, circuits, efficiency.
- Design: Why we make our lights the way they are and what we use.
- Purchasing: Questions about the purchasing process.
- About LED Grow Lights: General information about LEDs and LED grow lights.
- Comparing Grow Lights / PAR / PPFD: Everything about comparing grow lights based on numbers.
Complete List of Frequently Asked Questions
Why Buy Black Dog LED?
- Why choose Black Dog LED?
- Why do Black Dog LED grow lights seem more expensive than some other LED lights?
- Who is Black Dog LED?
About Black Dog LED lights
Spectrum / Color
- Why don't we have different vegetative / flowering lights?
Can Black Dog LED grow lights be used for both vegetative and flowering growth? - Do different plant species or varieties require different spectrums?
Do our lights work with all plants? - Are Black Dog LED grow lights full-spectrum?
- Why do we include ultraviolet (UV) in our LED grow light spectrum?
- How much UV light do PhytoMAX-2 LED grow lights provide?
- Why do we include green in our Phyto-Genesis Spectrum®?
- What is the Correlated Color Temperature (CCT) of Black Dog LED lights?
Usage
- What is the right size Black Dog LED light for my needs?
- Which PhytoMAX-2 LED grow light is equivalent to a 1000W HPS or MH?
Which PhytoMAX-2 light do I need to replace my existing grow light? - How deep can our LED light penetrate plant canopies?
- Why don't all of the diodes on my Black Dog LED panel light up?
Why do some LEDs appear dim? - How high above the plants do I need to hang the light?
- Are there any differences growing under Black Dog LED lights compared to HPS?
- What temperature should I run when using Black Dog LED lights?
- Does growing warmer hurt the flower quality?
Will growing at higher temperatures cause insects (spider mites, thrips, etc.) or powdery mildew to reproduce faster? - How many plants can I grow under a light?
- Why are vegetative footprints larger than flowering footprints?
- What are the vegetative and flowering footprints based on?
- Do LED lights cause magnesium deficiency?
Is it normal to see purple streaks on the stems / petioles? - How much will it cost to run LED grow lights?
- How much heat will the lights produce?
How much cooling / AC will I need? - Where can I find information about the Black Dog LED Universal Series lights?
- Where can I find information about the Black Dog LED original PhytoMAX Series lights?
Electrical
- What is the efficiency of PhytoMAX-2 LED grow lights?
- Do Black Dog LED lights work with 220V / 240V?
- Is it less expensive to run at 240V?
- How many lights can I run on a circuit?
- Will Black Dog LED lights work in my country?
Design
- How do we choose our diodes?
What diodes do we use? - Why don't we have a glass sheet or secondary lens under our LEDs like every other LED grow light?
- Why do we have fans in our lights?
Aren't passively-cooled LED grow lights better? - What is the difference between original PhytoMAX and the new PhytoMAX-2 LED grow lights?
- Why do we use primary lenses?
- Why don't we use secondary lenses / optics?
- Why don't we use dimmers?
Purchasing
About LED Grow Lights
- Do LED grow lights put off heat?
- What is the difference between "LED Watts" and "True Watts"?
- Are white LEDs efficient for growing plants?
What about these 10-watt white LEDs? - What is beam angle and why is it important?
- What is the difference between 1, 3, 5 and 10 watt diodes?
What are COB LEDs? - Do LED grow lights require a ballast like HID lighting?
Comparing Grow Lights / PAR / PPFD
- How can I compare different grow lights?
- What are lumens, and are they useful for evaluating grow lights?
- What is PAR, and is it useful for comparing grow lights?
- What is the difference between photon flux (PF / PPF) and photon flux density (PFD / PPFD)?
- Which is more important- total photon flux (PF / PPF) or photon flux density (PFD / PPFD)?
- How should PAR / PPFD measurements be taken and compared?
How are PAR/PPFD measurements often manipulated? - What is YPF, and is it good for comparing grow lights?
- What is Correlated Color Temperature (CCT), and is it good for comparing grow lights?
- What is Color Rendering Index (CRI), and is it good for comparing grow lights?
- Which is better- UVA or UVB?
- Why don't "98% reflective" HID aluminum reflectors actually reflect 98% of the light toward your plants?