I am currently designing a commercial grow facility. I want to use 1000w DE Phantom Open Reflectors. I’ve read and watched many different views. Some recommend the simple 4x4 or 5x5 footprint, I also see umol equations, w/ft². What is the best way to determine how many grow lights to put over my canopy?
Canopy size: 44’x40’
Canopy height: 7’
Ceiling height: 12’
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Is this strictly an indoor commercial grow, or are you also leveraging sunlight in a light dep greenhouse?
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This is strictly indoor
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Best to measure as PAR/μmol. 800-1100 μmol at canopy is a common range for flowering. Good lighting companies will be quick to help you develop a lighting layout that will detail μmols, total watts, BTUs, etc. If you choose a good LED company you can ditch the re-lamping costs, use less power, have less heat, provide consistent full spectrum, and be much more environmentally responsible. Shy away from any company that doesn’t provide PPFD/μmol levels on their specification sheets. Review μmol/j figures so that you get an efficient fixture. Review spectrum charts and look for healthy levels of red, blue with yellow and green. Review data from 3rd party testers such as the Design Light Consortium. Contact your local power company before you purchase and ask about rebates and even on bill financing. Checkout https://sage.lighting/ or contact Brian Gandy @BG_SAGE here, he’s a wealth of info. If you are curious to see an LED layout to compare, let me know and Illumitex can work one up. Cheers!
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I highly recommend getting the ballasts out of the room. I like to put them in the hallway outside the room to minimize heat load. This also affects humidity and dehumidifier load due to the drying action of A/C.
The Magnum XXXL hoods have a good 5’x5’ footprint. 16-20 sites per light in 6"x6" rockwool or 1 gallon pots works for that. I haven’t used the below reflectors, but something like them may do well:
The reason I like them, and will evaluate them for my next design is because I typically remove the glass to reduce light/uv reduction on the plants and allow ambient air to cool. Makes for a cleaner installation as well.
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Check this out. Rudimentary and limited on fixtures but should help:
https://www.hawthornegc.com/tools/lighting-tool
It’s all about your target light level, heights of canopy, ceiling benches etc and work backward from there. Gavita used to recommend 6’ x 7’ but lots of variables in play.
HMU if you need any more help. Or if you want to consider LED
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High Five 
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I’ve used that and the one and the hydrofarm calculator which was good cause it had the Phantom reflector. Sometimes I would input the same numbers on the Hawthorne calc and it would give different outputs.
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Yea @Fizzikkz , each one has it’s own ies file compilation and also then programmed differently on the back end by each vendor. Good ballpark starting numbers for someone getting going.
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We’ll do a complimentary free facility review, provide a best in class LED that has proven capability (references), along with a Consultation on design configuration and recommended number of LEDs. Contact Tom at PowerTrakGrow, tmihalko@powertrakgrow.com. Our lights are producing 2.5-3.0 grams/watt with record THC concentrations. 4th Generation LED crystals.
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Hi Todd @Fizzikkz
How many grow lights and how to position them depends a lot on the capabilities of the fixtures themselves. You really want to make sure there is a nice and even uniformity of PPFD across all points within the footprint, which is difficult for most lights to achieve without using optics on the diodes. Check the light’s PPFD chart to show multiple readings to make sure you aren’t just seeing an average of the hot and cold spots.
For what it’s worth, our team offers photometric calculcations of your facility to help you determine the proper light levels and how to achieve them with lighting specifications. If you’d like to send us some floorplans or layouts you’re considering, we can set up a call and run some calculations.
Good luck!
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With numbers like that it seems that on a per-watt basis, tunable LED has the lead in yield over HPS @1.36 g/w by my calculations.
However, at top yields and $1,100/lb wholesale that translates to a revenue of $132/sq ft (which is how the real estate is valued), for 1,000 W DE HPS vs $43.64/sq ft for 150W LED.
Of course, one would have to factor in product quality (affects wholesale price), as well as energy cost and equipment differentials for the light fixtures and A/C.
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Optional wattage, at 320 and 515…
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