Bare bulb PAR ratings for 600W HPS

Hey there growers!

I've been debating with others regarding optimal distance plants could be from a bare 600W HPS (specifically the diameter of a vertical grow using 2 600W HPS bulbs). Lumen numbers and the inverse square law are often cited by both sides, but one side believes that the dimensions put to use will optimize square area and overall bud growth, while the other side believes that space should be decreased, met with light movers, 3-4 600W bulbs instead of two, or a myriad of other options that neither side can confidently prove would end up being more or less cost efficient for how much it would yield. It would be nice to be able to afford the electricity to run 2-3 boxes of exact dimensions each with separate singular variables to put an end to our discussion after one grow.

For specific background information, I'll provide our exact specs.

box is 5'W x 6'L x 6'H. Pots are 6" each, so in a vertical array that reduces our area to 4' x 5' x 6'. Plants will grow towards (obviously) leaving some amount of distance from pot to actual canopy, further reducing the actual diameter of canopy that the lights would be required to cover. I've seen plenty of larger vert set ups with diameters of 5-7 feet with a height of 6-8 feet, using 2-3 600W HPS and believe that it can be done with the above dimensions we would use.

That being said, I have a few specific questions.

1. Does anyone have any source of information detailing PAR readings for 600W HPS bulbs when not used in a reflector? I have found several private experiments done using hooded lights (unsure if they used glass or not either though), but I would like to find real numbers comparing the two, as our bulbs will be hung bare in a vertical array rendering the data with hoods useless for us.

2. What are others' opinions on vertical grows' diameters using 600W bulbs?

I just have such a hard time, even regarding the inverse square law, believing that it would be more efficient to use more wattage for that area, or to decrease our potential growing area by reducing the diameter of the canopy when others have done so VERY successfully withing similar/larger specs while I often see many that grow in all too cramped vertical arrays (we have currently subjected ourselves to this with a canopy just shy of 3' in diameter).

Thanks for any tips in advance!

Hmn I'm looking for a hood myself did you get a vert ?

http://growershouse.com/blog/hid-bulb-test-comparison-review-hortilux-ushio-digilux-baddass-solistek-lumatek-maxlume-growlite-ultra-sun/

these are for 1000w though. it depends on the bulb, reflector and distance. I do know the 600w ushio is 1100 µmoles at 12 inches away. theys have very poor cri and spectrum. cri is around 35. where cmh , led , induction cri is 80-93. the higher the cri the more even the spectral distribution. par isn't everything. my old apollo led has higher µmole/s then my inda gro. My IG kicks the shit out of the apollo. More even spectrum... plus it puts out uv-a , uv-b and IR which led and most hps don't.

watts and lumens doesn't mean anything. its all about efficiency. par, spectrum, and cri.


I used to do vert bare bulb with cmh. Philips allstart 330's. 2 of those matched my former 1000w in yield but better quality

Thanks, Hyroot!

I have looked over growershouse's articles more than several times, and it was what initially led me to seek similar data regarding bare bulbs without a reflector. I hope I wasn't misleading you in thinking I was specifically debating using bulbs rated at varying lumens/watts as the choice for this grow is 600w HPS, using non ideal ballasts/bulbs unfortunately.

I definitely understand the benefits and shortcomings of the various lighting options out there, but again I am limited to using the aforementioned lighting

I've briefly looked into the induction lighting systems out there, but have discarded them for the time being as I plan on sticking with the basic ballast/HID system, but they are very intriguing. Any noted benefits right off the bat for you? Also, do you have a journal documenting your CMH vert? That sounds very interesting

Anyway, hope I didn't come off as standoffish; I think you may have just misunderstood my inquiries or my intent. Thanks for dropping some knowledge around here!

I was giving you an idea how par, cri, spectrum all correlate to each other. Where its not just one measurement. I have a somewhat older thread with hps, CMH, and par t5. Search hyroots rols no till. I am now running induction and led . Originally I like induction but I was turned off by the lower par numbers. I now like it quite a bit. It is expensive upfront. In the long run with no bulb replacement and less electricity costs its far cheaper. One light pays for itself in 1 year just from electricity savings. I'm not trying to steer you any way. I would recommend CMH over hps. They last 2-3 times longer and degrade less than hps. CMH have a ceramic arc which degrades less and takes about 1.5 years to degrade and distributes spectrum / light evenly. Where hps has an aluminum arc and starts degrading after 6 months of 12/12. Has very poor light distribution. CMH are open reflector rated with a quartz crystal coating for protection. They run far cooler in temp. They only run on mag ballasts. CMH have high par and cri. Allstart 330 1360 umole/s at 16 inches and 90 cri. Allstart 860 1835 umole/s at 32 inches and 93 cri.

link to my current thread is in my sig.
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