PhytoMAX-4 General Information

Differences between SP, SC and SX models

The only differences are in the power cords and what voltage the lights can handle:

  • SP Models utilize a standard IEC power cord and are rated for 100-250VAC input.
  • SC Models utilize a locking, water-tight power cord and are rated for 100-277VAC input.
  • SX Models utilize a locking, water-tight power cord and are rated for 347VAC input.


  • Inspect the light for shipping damage. Do not plug in a light that has suffered shipping damage without consulting us first.
  • Remove the protective film covering from the glass before turning the light on.
  • NEVER look directly at the LEDs while they are on; eye damage may result. They’re very bright!
  • We recommend wearing any UV-blocking eye wear such as sunglasses when viewing or working with plants under our lights. PhytoMAX-4 contains UV LEDs, which just like natural sunlight can irritate and damage your eyes.
  • Don’t over-load your electrical circuits- a PhytoMAX-4 24S light won’t run on a standard 15-amp, 110V household circuit! For more information and advice, consult your electrician.

Issues and Questions

Black Dog LED wants you to be satisfied with your PhytoMAX-4 light!

  • Please note that our LED growing lights contain infrared and ultraviolet diodes that are outside of humans’ visual range, so it is normal for some of the LEDs to appear dim or unlit.
  • Our lights have a soft-start feature that takes up to 1 minute to achieve full brightness. This is a safety feature to protect your eyes in case you’re looking at the LEDs when they first turn on.
  • If you have any questions or issues with your lights’ function, please contact Black Dog LED, not the store it was purchased from

Hanging the Light

  • We recommend tying a stopper knot at the lose end of the rope to prevent over-extension of each of the ratcheting rope hangers.
    Ratchet rope with knot
  • Ensure that the structure you’ll be hanging the light from can support its weight plus some extra for cords, etc.
    Light Weight
    PhytoMAX-4 2S 4.1 kg
    PhytoMAX-4 4S 10.9 kg
    PhytoMAX-4 8S 11.8 kg
    PhytoMAX-4 12S 12.7 kg
    PhytoMAX-4 16S 19.5 kg
    PhytoMAX-4 20S 20.4 kg
    PhytoMAX-4 24S 21.3 kg
  • Insert a metal hanger clip into the hanging bracket either side of the back of the light. Ensure that both ends of each clip are secure.
  • Clip one end of each of the ratcheting rope hangers to the hanging/anchor point on the ceiling, and the other end to the metal hanger clips attached to the light. The ropes should be hanging straight, not pulling the hanging brackets toward or away from the center of the light.
    Correct hanging
    Incorrect hanging
  • Adjust the ratchet to hang the light at the recommended height.
  • Ensure there is always a minimum of 15 cm / 6 inches of clearance on both sides of the light that have vents. Failure to provide adequate clearance can cause the light to overheat. The sides without vents and the top of the light do not require any clearance.

Coverage Area & Hanging Height

PBFD / DLI Calculator

Please enter the size area you want to grow in, or the size footprint you're looking for each light to cover:


Footprint area:
Light ModelHanging Height (inches)Average PBFD (μmol/m2/s
PhytoMAX-4 2S--
PhytoMAX-4 4S--
PhytoMAX-4 8S--
PhytoMAX-4 12S--
PhytoMAX-4 16S--
PhytoMAX-4 20S--
PhytoMAX-4 24S--

Hanging height is the height the light needs to be hung above the average top of the canopy to allow the light to spread out and cover the footprint you specified, and does not vary with the light model. For larger areas, using muliple smaller lights (each with a smaller footprint) reduces the required hanging height. PhytoMAX-4 lights can be flush-mounted to the ceiling and are only 4.5" / 11cm thick.

The PBFD levels given are the average for every square inch of the footprint you specify. All light intensity calculations assume reasonably-reflective walls around the footprint and/or adjacent lights on identical footprints. This calculator is intended to guide you to the right size light for your situation, but we're always here to help- you can always contact us for advice.

We have custom, proprietary light modeling software that can show you guaranteed light intensity levels for every square inch of your growing area, or even every cubic inch from top to bottom. Contact us through email or phone or schedule a large-project consultation.

Recommended PBFD Ranges

The ranges given below are guidelines based on our years of experience. You can go lower or higher in some circumstances; you can always contact us if you want to talk about unusual set-ups.

The "Min" light level is the minimum we would think you would be happy with for decent results; "Typical" is what we would generally recommend and "Max" is on the higher end of what we would recommend. PhytoMAX-4 lights can be dimmed, so you can always get a bit more power than you need and experiment.

Recommended μmol/m2/s PBFD
Growth StageMinTypicalMax
Cloning5075 - 100150
Seedlings200300 - 600700
Vegetative200300 - 600800
12 hrs/day
No CO2
350600 - 750950
12 hrs/day
With CO2
800900 - 13001800
12 hrs/day
With CO2
12001500 - 18002500 **
20 hrs/day (autoflower)
No CO2
200350 - 450600
20 hrs/day (autoflower)
With CO2
450600 - 7751000

** This light level is only recommended for experimentation or research purposes- it is not recommended for a production facility. Driving plants with that much light requires a lot of attention to fertilization, CO2 and environmental conditions- it is much more likely that something will go wrong and cause complete crop loss. We've tested light levels like this ourselves- which is why we don't recommend it in general, though we did get 137 grams/ft2 for a 6' X 6' area at 2200 μmol/m2/s PBFD. PhytoMAX-4's unique design can deliver even higher light levels if you desire to really push limits, but we haven't seen any practical benefit yet.

Growing tips / maximizing yield

There are two important differences when growing with PhytoMAX-4 LEDs:

  • We recommend keeping your growing area 5 °C warmer than you would with other lights to maximize yield.
    • This is because our lights are designed for plants, not humans.
    • For more information, see our complete study on leaf surface temperature and grow lights.
  • If not growing hydroponically, we recommend using fabric pots with our lights; they allow soil to dry out more quickly since our lights aren’t heating it as much. This allows faster nutrient cycling and encourages a better root system.
  • If you are going to burn sulfur in your growing area, remove the lights from the area, or turn lights off and seal in plastic during the sulfur treatment. Failure to do so will void your warranty!

Cleaning and maintenance

If your light requires cleaning:

  • Turn off the light and disconnect the power cord.
  • Spray an ammonia-free glass cleaner onto a soft lint-free towel and gently clean the glass.
  • Allow to air-dry, then plug your light back in and turn it on.
  • NEVER spray any liquids directly onto or around the Light!

NEVER expose the light to caustic or corrosive chemicals, including sulfur sprays or fumes from burning sulfur; this will invalidate the warranty!


Common to All PhytoMAX-4 Lights:

AC Voltage Range 100 – 250V (SP models)
100 – 277V (SC models)
347V (SX models)
AC Frequency 50 / 60 Hz
Operational temperature range -20 to 40 °C
Dimming 0 – 10V, 15% – 100%, dim-to-off
Spectrum Phyto-Genesis Spectrum® covering 350-750nm, including UV and IR
Warranty 5 Years
Certifications UL1598, UL8800, ETL, CE, FCC, RoHS
Power Factor > 0.99
Fans 70,000 hour minimum expected life

Designed and Assembled in Colorado, USA

The Phyto-Genesis Spectrum®:

Phyto-Genesis Spectrum

Model Specifics:

Light Wattage (average) Total Fixture Photon Flux (μmol/s) # LEDs BTUs Size (LxWxH) (cm) Weight (kg) Amps (average) at 230V
PBAR (280-800nm) UV (<400nm) PAR (400-700nm) IR (>700nm)
PM4-2S 125 266 8 238 20 56 426 22 x 22 x 11 3.6 0.54
PM4-4S 250 531 16 476 40 112 853 37 x 37 x 11 7.7 1.09
PM4-8S 500 1062 31 952 79 224 1705 37 x 37 x 11 9.1 2.17
PM4-12S 750 1594 47 1428 119 336 2558 37 x 37 x 11 10.4 3.26
PM4-16S 1000 2125 63 1904 158 448 3410 48 x 48 x 11 17.7 4.35
PM4-20S 1250 2656 78 2380 198 560 4263 48 x 48 x 11 19.1 5.43
PM4-24S 1500 3187 94 2856 237 672 5115 48 x 48 x 11 20.4 6.52

Total flux numbers from integration sphere tests of the entire fixture. Note that total photon flux is the entire photon output of the light (PF / PPF, in μmol/s), and not the measurement at a particular point under the light (PFD / PPFD, in μmol/m2/s). When measured at a particular point, the PFD / PPFD can be much higher or lower than the total photon flux.

Transitioning plants from other lights

When switching plants grown under other lights to PhytoMAX-4’s Phyto-Genesis Spectrum®, some shock and/or stalling can occur, as with moving plants between any other different lighting situations. Our LED grow lights are very intense and contain UV light (unlike many grow lights), either of which can shock plants not used to such lighting.

To adapt plants to our lights with as little shock as possible, hang the light at twice the recommended hanging height to start. Each day for about a week you can lower the light by 15-20 cm until it is at the recommended hanging height and your plants have adapted.

When starting seeds under our lights it is fine to use the normal footprint and hanging height; when seeds germinate they adjust to the lighting conditions they first experience. Raising the hanging height of the light higher than normal during germination can lead to leggy, weak seedlings.