General Survey of hps 600 watt light users: What is your Lux value at 1 meter from the bulb centre

[buzz62]

High, hopefully everyone hasn't converted to LED yet! I recently found out my analog Lux meter needs calibration, and my luck with app lux meters is not one of trust! So what I would like to know is what other users are reading in Lux from their 600 HPS at 1 meter. I know that older bulbs can output considerably less over time, so if your bulb is older please mention it. Thanks All !

My 600 W Fusion Bright Super HPS in a quartz cool tube reflector with 1000 hours is reading 12,000 Lux on my questionable meter, and about 12,700 -22,000 using the camera and whiteboard method depending on which formula you use. Hence my confusion! Some other growers pointed this out so I am conducting this survey. Thanks for participating.

 

[TorturedSoul]

Might want to have folks include the brand/model of bulb, too, since different manufacturers will tend to use slightly different mixture of gases... which will cause the output to be slightly different in color / spectrum - which will affect lux readings. For example, if a certain bulb has a higher portion of its output in the green portion of the spectrum, that'll tend to cause it to read higher (on a lux meter). It'll also tend to give poorer performance when used to grow plants, lol. Trying to compare different brands of lighting with such a device (and get useful information) is... well, it's kind of an apples to oranges thing.

Another thing you'll probably want to know is whether the people who post their results are using an open reflector or an air-cooled one, because a sheet of glass could attenuate the bulb's output up to 9% or so (and possibly cause a very minor shift in the practical spectral output, but I cannot remember that part - sorry, the mind is a bit crunchy around the edges ).

 

[buzz62]

Might want to have folks include the brand/model of bulb, too, since different manufacturers will tend to use slightly different mixture of gases... which will cause the output to be slightly different in color / spectrum - which will affect lux readings. For example, if a certain bulb has a higher portion of its output in the green portion of the spectrum, that'll tend to cause it to read higher (on a lux meter). It'll also tend to give poorer performance when used to grow plants, lol. Trying to compare different brands of lighting with such a device (and get useful information) is... well, it's kind of an apples to oranges thing.

Another thing you'll probably want to know is whether the people who post their results are using an open reflector or an air-cooled one, because a sheet of glass could attenuate the bulb's output up to 9% or so (and possibly cause a very minor shift in the practical spectral output, but I cannot remember that part - sorry, the mind is a bit crunchy around the edges ).

Thanks! Yeah, I guess its a pretty broad spectrum of possibilities. I do have a quartz cool tube in mine. And I guess most lux meters were generally designed for full spectrum light, which is why I seem to get whack (high) readings on my red/blue/UV led light.

 

[TorturedSoul]

In theory, when comparing lights using the same general technology and wattage (such as a dozen different 600-watt HPS bulbs from 12 different manufacturers), the one that scores lowest on a lux meter might be the best at growing plants, lol. Since its output is probably less "focused" in those portions of the visible spectrum which appear brightest to the Mark I eyeball, human (higher weights are given to those portions, since that's what lux / lumens / luminious flux are all about in the first place) and, therefore, there is a greater possibility that more of its output is in that range which we refer to as PAR.

In other words, the lux meter will be heavily green-biased. Not a whole lot of green in a good grow light. . . .

 

[Mars Hydro]

Lumen is for human while Par is for plants, but usually the higher lumen means higher par as well. Not the highest number is the best, plants shows slow growth for both lack or too much of the light. So to find the best data and height for plants growth is more reasonable,

 

[buzz62]

Thanks for posting! Most analog light meters were designed for steady state full spectrum sunlight, and as a relative indicator work just fine. They do not work very well with coloured led's due to spectrum distribution, nor led's that are cycling at 60 Hz but they do work with full spectrum COBs a bit better.
Anyway, I am looking for other peoples 600 watt HPS lux measuments, not more discussion about lux verus par versus ppfd vesus foot candles, as that has been discussed to death on this forum!!