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I’ve had my head down, buried in building a Growmau5 inspired LED fixture for my 6×6 flowering room (Mega thanks and props to Growmau5, I owe you a smoke out homie). I’m pretty happy with how it turned out. Thought I would share it with the group and say upfront any DGC who wants to copy the design for personal use is welcome to do so. I’ll be happy to answer any questions about it.

My goal was to build a fixture custom sized for my room’s exact dimensions, that would produce slightly more light than even the most light hungry strains of cannabis can use effectively. It also had to be more electrically efficient at making that light than a Gavita DE on full power. I.E. the “LED Gavita Slayer.”  I am not claiming this fixture puts out more light than a Gavita DE in total, but I bet its close(see update below). It does, however, cover a larger footprint than a Gavita with as much light as can be used, even with CO2 added. It is a few percent better at converting a watt of power from the wall into light than a DE, and does not emit anywhere close to the amount of unusable infrared light all HPS creates . It does not heat surfaces directly and then soak heat into a room or leaves like HPS does. For those who are unfamiliar with COB type led arrays, each one of these emitters is roughly equivalent to about 80-90w of HID at the level I’m driving them. Another reason I believe this fixture earns the “Gavita Slayer” title is the fact that with the multiple emitters and Khatod 90 degree lenses, the slightly excessive light is very evenly spread across the entire room. Calculations that were graciously done by Growmau5, and then again by Robin at Northern Grow Lights, show it should produce 1000+ ppfd across the entire canopy, wall to wall, with very minimal, if not zero hot spotting.  I expect it to penetrate into a properly trained canopy around 24″. There is enough overlap and light coming from every angle to minimize shadowing, adding to its ability to get sufficient light deep into the canopy.

Here’s where it doesn’t seem to slay a Gavita. Initial cost. However, it will pay for itself on the first run if used properly, similar to a Gavita DE.  Growmau has achieved nearly 2 grams per watt with a similar design, averaged between multiple strains, none of which were massive big boy style yielders. We each have approx the same level of evenly spread output. If we use his grow and yield as a model, and then calculate using a more conservative yield of 1.75 gpw, this light is capable of about 2800g or 100 Oz’s per run. Then, if we figure a $200 savings or profit, whichever is your thing, on each Oz ($100+ under market in my area) we have $20k. Way more than the $3700 it cost to build it.  Even at a very paltry .5 gpw of production it makes $5700 worth of value per cycle. Most new growers pull .5pw on their first successful run with any decent lighting.  LED is more than cost effective for growers with 8ft or lower ceiling heights IMO.

Parts List for the LED Nerds:

20 Cree Cxb3590 3500k CD bin cobs. Bender & Wirth 449 holders. Khatod 1825 90deg lenses. SST-140 drilled and tapped heat sinks from NGL. Sureseal TIM pads. Meanwell hlg320-c2100b’s. 1/8″ aluminum sheet stock for the bars was ordered cut to size and bent to spec from Metals Cut 4 U. 3″ holes were drilled/cut using a hole saw and drill press to allow the lenses to pass through. All output wiring and connections are 14 or 16awg, soldered, and finished with heat shrink.  AC input was split between two cords allowing 3 drivers to run on one circuit and the other 2 on a second circuit. I only have a 100amp panel to run this fixture and the rest of the house from. Future plans include an upgrade to 200amps of service, then add a 220v 20a drop to the driver board and a second 15a 110v circuit to the room, giving me separate 15a 110v circuits for both the veg and flower room.

It will be full on Disco Mode then….lol…… and Mr Scott will finally stop screaming at me from the engine room all the time…

Cheers, hope yall enjoy…..

Driver and Junction box board with 5 Meanwell HLG-320 320w drivers.

Driver and Junction box board with 5 Meanwell HLG-320 320w drivers.


View of the top side of the light bars. They nearly cover the full footprint of the room. There is approx 6″ between them and the walls. They can be raised another 6″ or so.


View of bottom of light bars.


This pic shows the intensity best. This Lil Cannalope kush is deep lush green under normal lighting. Looks lime green in this pic with fixture on full output.

Update: I sent a link to this post over to Robin at NGL, and asked just for grins if it actually would have more output at the canopy than a Gavita DE on max output if both were over a 4×4 and at appropriate heights for each fixture….. I bout shit myself at his answer…. He tells me two bars alone will out do a Gavita DE. All 5 bars in a 4×4 would be equivalent to midday summer sun. HOLY SHIT. I knew it was strong, but damn, it actually is a Gavita Slayer…Double Gavita Slayer at that…. “We just need more power Captian!”