is this lumen chart wrong?

Hi , help me understand this.
1 lumen/m2 = 1 lux = 0.1 candles/ft2

Sunlight is about 100000 lux = 10000 candles/ft2

The chart says that for 1000w HPS at 12 inches you should have 44563 candles/ft2 = 445630 lux = 4 times brighter than sunlight. Isn't that wrong or am i not understanding something right?
Does someone know how many lux does a 1000w HPS give at 12 inches?

I think what its saying is that those lumens at that distance is in fact 4 times the strength of the light we are receivingthrough the atmosphere after all said and done. What the plants would normally take. Not the strength of the sun. So at that output you'd want it around 25-26 inches to get closest to those lumens. But it's not the same spectrums as the sun. It can handle that power at that color but with the high yellows it risks burning the plant closer than around 26 inches according to the chart

the strength of the sun is 6840000000000000000000000000 lumens , 100000 lumens/m2 is what we get on earth.
I bought a lux meter , cause i want to check on my lights and ballast health , what lux i am really getting at 12 inch from bulb. I am getting 50000 lux at 12 inches witch seems reasonable. But the chart says i should be getting 500000 lux at 12 inches witch seems wrong.
I would really like a chart if there is with lux at deferent distances that HPS1000w sould give in new condition , or some way i could calc it.

They night be using like gavitas or something but ill look into it more and try to figure it out as an led grower I only look into this kinda stuff when it comes up lol

nonstop said:

Hi , help me understand this.
1 lumen/m2 = 1 lux = 0.1 candles/ft2

Sunlight is about 100000 lux = 10000 candles/ft2

The chart says that for 1000w HPS at 12 inches you should have 44563 candles/ft2 = 445630 lux = 4 times brighter than sunlight. Isn't that wrong or am i not understanding something right?
Does someone know how many lux does a 1000w HPS give at 12 inches?

[URL=https://www.icmag.com/ic/picture.php?albumid=53360&pictureid=1425610&thumb=1]View Image[/url]

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"At midday in mid summer the sun can reach around :-
2000umol/m2/s = 9800FC = 1060W/m2 = 106000LUX."
taken from http://autogrow.com/general-info/light-measurement

measuring lux or ft candles is not accurate but can give you a relative idea useful for comparing new bulbs or aging of bulbs.

with a par meter i have gotten 2000 umols on a bright, clear, sunny day but anything over that you are causing photoinhibition. it is easy to do indoors. and 12" with a 1k hps is too close.

since the highest rate of photosynthesis in cannabis occurs at 1500 umols that is probably what you should be aiming for at the closest part of the plant.

that occurs with a new hortilux 1k hps at about 16". same distance fc reading should be in the 7350 fc range and for lux it's around 79,500 lux.

the chart is whacked.

thanks allot for the answer delta9nxs. I am actually all over your PPK threads , i m planing on trying a 1 plant ppk next round based on your thread , as my first attempt in hydro. Your plants get huge!!!
So back to this thread could you answer one more question ?
My lights are very old HPS and magnetic ballasts so instead of having 79500 lux at 16 inches , i have 50000 lux at 12 inches. Is that still to close? I use cooltoobs so there is not much heat on the plants. I mean, the older the lamp gets the closer you should be able to get , right? I am so persistant on the 12 inch cause my grow is vertical with nets that hold the plants 12 inches from the lights. I don't have space for more distance.

nonstop said:

thanks allot for the answer delta9nxs. I am actually all over your PPK threads , i m planing on trying a 1 plant ppk next round based on your thread , as my first attempt in hydro. Your plants get huge!!!
So back to this thread could you answer one more question ?
My lights are very old HPS and magnetic ballasts so instead of having 79500 lux at 16 inches , i have 50000 lux at 12 inches. Is that still to close? I use cooltoobs so there is not much heat on the plants. I mean, the older the lamp gets the closer you should be able to get , right? I am so persistant on the 12 inch cause my grow is vertical with nets that hold the plants 12 inches from the lights. I don't have space for more distance.

Click to expand...

that roughly corresponds to 1000 umols so you should be ok.

i've run new 1k's in cooltubes that close before.

thank you for considering the ppk!