LED lights, lumens, intensity

It is my current understanding that I can not use a lux meter to measure LED lights as relating to cannabis.
Assuming that is correct, how do I measure LED light intensity and at what intensity do I maintain my LED lights during flower?

Thanks in advance


@dbrn32 would be able to help.


Good to see you posting @Tarzan!

It really depends on the led you’re trying to measure. Lux is measure of photometric energy per square foot. The scale for measuring this is weighted to green wavelengths because that’s what our eye is most sensitive to. So a lux meter will prioritize green wavelengths over all others, and not give an accurate reading as to intensity of other wavelengths.

Plants on the other hand process radiometric energy. A red or blue led will usually have a higher radiant flux than photometric flux. Or at least we can say that a lux meter won’t represent the radiometric energy properly.

So, if you have led panels constructed of mostly red and blue leds the lux meter is indeed relatively useless. To measure the intensity accurately you would need a quantum par meter. I think they start around $300 or so. If you have led panel that is mostly white phosphor coated leds, you can probably find some ballpark lux data or a conversion.


An old one


Thank you for your responses!
You certainly verified my suspicions.

Imagine me searching the web for hours trying to figure out how to measure LED intensity with my handy dandy light meter.

Just couldn’t find the solution. And you knew right off, way to go.

I currently have my LED lights at 24". I had them lower yesterday and my taller plants leaves were "reaching for the light, pointing up at a non-typical angle.

Seems I remember that as being a symptom of light burn.

Thanks again you guys, as usual the ILGM team comes through!


ps. the monkey says hey.

Cheetah, a chimpanzee who starred alongside Tarzan in the franchise films of the early 1930s, died Saturday. He had experienced kidney failure earlier that week, and was thought to be 80 years old.

Cheetah, also known as Cheetah-Mike, acted as Tarzan’s comic sidekick “Cheeta” and was one of several chimpanzees who appeared in the films of 1932 to 1934, with Johnny Weissmuller in the starring role.

Around 1960, after living on Weissmuller’s estate, Cheetah retired to Suncoast Primate Sanctuary in Palm Harbor, Fla.

“It is with great sadness that the community has lost a dear friend and family member,” the sanctuary announced this week on its website. Chimpanzees live an average of 45 years in the wild, and captive chimps have an average lifespan of 60 years.

While at the sanctuary, Cheetah enjoyed watching sports on television, listening to nondenominational Christian music, and occasionally throwing poop when he was feeling disgruntled.

“He was very outgoing,” outreach director Debbie Cobb tells PEOPLE. “He always loved to laugh and to make other people laugh. He was the first chimp I’ve ever seen shed a tear when another animal died.”

Cobb, who has been affiliated with the sanctuary since she was a child, has known Cheetah for 51 years, and says she will miss “not being around him everyday.” The sanctuary has been raising funds to construct a medical building dedicated to Cheetah. “We’re going to make sure that Cheetah’s memory lives on forever,” Cobb says.

Actress Mia Farrow, whose mother, Maureen O’Sullivan, starred as Jane in the Tarzan films, took to Twitter to remember the animal.

“Cheetah the chimp in Tarzan movies died this week at 80,” she wrote. “My mom, who played Jane, invariably referred to Cheetah as ‘that bastard.’”

“He loved women,” Cobb says. “He loved life, everything about it.”

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