Do LED’s promote cal-mag issues

cdgmoney250 said:

Back to the topic of lighting spectrum and intensity effects on quality…

Many people have cited Dr. Bruce Bugbee & Mitch Westmoreland talking about the effects of light spectrum on secondary metabolites, or the lack there of… I just watched the Bugbee/Migro podcast from earlier this year where Bruce said they found no cannabinoid differences between different lighting spectra, though from his own study the results show a 10% difference in CBD between HPS & LED (no difference in THC) but whatever.

I know I’ve mentioned it before and I’m likely going to ruffle some feathers, but theses dudes are NOT the ultimate authority on cannabis science. Some of what they say just isn’t representative of drug type cannabis (they both grow non-THC hemp), and their methods serve to show the shortcomings of not only their experiments, but the conclusions one can draw from them regarding drug type cannabis.

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For some time, Bugbee's research was restricted to low THC cannabis but the Federal Government changed licensing and he's been using standard strength cannabis for a few years now. I think it's been a few years but I can't cite a source for that.

Delps8 said:

For some time, Bugbee's research was restricted to low THC cannabis but the Federal Government changed licensing and he's been using standard strength cannabis for a few years now. I think it's been a few years but I can't cite a source for that.

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It was actually from this video starting at 13:00 minutes in where he’s talking about it. Granted the video is 5 years old, he makes a statement in the migro interview from earlier this year basically telling people to prioritize electrical efficiency over spectrum, but that misses the point of growing a medicinal crop if we don’t cultivate all the possible compounds each plant has to offer. An electrically efficient spectrum might grow subpar plants compared to a more broad and balanced spectrum, which is less efficient. Just gotta decide which is more important.

From my personal experience , They absolutely demand more in my setup . I believe it’s magnesium but don’t quote me on it . I actually have to dial my main nutes back , to allow more calmag , to keep my four auto flowers in coco loco / 9 gallon xxl autopot system and a kind x750 wide open on the full spectrum and currently 50% on the uv /ir . I had the same experience with 60/40 coco/perlite last grow as well .

Sounds like a cation imbalance in your coco. Potassium (K) and Sodium (Na) are highly competitive with Ca and Mg, and coco coir happens to naturally come loaded with K and Na. It’s usually why coco has to be buffered with calcium prior to use. This seems to be a more prevalent issue with people growing in soilless media following feeding guidelines, at least to me anyways.

cdgmoney250 said:

Sounds like a cation imbalance in your coco. Potassium (K) and Sodium (Na) are highly competitive with Ca and Mg, and coco coir happens to naturally come loaded with K and Na. It’s usually why coco has to be buffered with calcium prior to use. This seems to be a more prevalent issue with people growing in soilless media following feeding guidelines, at least to me anyways.

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coco loco , is treated as soil . It’s not pure coco . Also the issue presents itself to the two very large autoflowers closest to the led - but the two shorter plants don’t have it .

DoubleD5374 said:

coco loco , is treated as soil . It’s not pure coco . Also the issue presents itself to the two very large autoflowers closest to the led - but the two shorter plants don’t have it .

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You can treat it however you want, but it’s still primarily a coco/perlite mix with a dash of forest humus and EW Castings. That means 50-60% of your media likely has a K & Na imbalance and will have more difficulty holding on to Ca and Mg due to this competitive nature. This means your base cation saturation ratios of your media are possibly out of balance too.

Plants closer to the light will have higher nutrient demands due to higher metabolic rate. If the nutrients aren’t readily available for uptake, the plant will show deficiency in the nutrients it’s having difficulty up-taking.

Magnesium is mobile within the plant and deficiency typically presents itself on older leaves due to nutrient translocation to newer growth.

The most common cause of these “I switched to led and now my plants are deficient” symptoms are usually transpiration related issues (your environment) or fertilizer imbalances.

cdgmoney250 said:

It was actually from this video starting at 13:00 minutes in where he’s talking about it. Granted the video is 5 years old, he makes a statement in the migro interview from earlier this year basically telling people to prioritize electrical efficiency over spectrum, but that misses the point of growing a medicinal crop if we don’t cultivate all the possible compounds each plant has to offer. An electrically efficient spectrum might grow subpar plants compared to a more broad and balanced spectrum, which is less efficient. Just gotta decide which is more important.

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Thanks for digging that up.

Ironically, I did a screenshot of that part of the presentation on "2022-05-01_09-49-10_PM".



"An electrically efficient spectrum might grow subpar plants compared to a more broad and balanced spectrum, which is less efficient. Just gotta decide which is more important."

"might"-no doubt about it. There might be a spectrum that doesn't grow "subpar" plants and, if there is, I'll be happy to make room in my tent!

Here is my opinion on why plants under a LED lighting system have a propensity to exhibit a cal/ mag def. ......... Traditionally we used HID lighting systems, these have served us well but just very wasteful with efficency. LED on the other hand is way more efficient and can focus on the key peak point in the spectral scale, while blending the specific wavelengths with a Kelvin class white light. Ie... 6500k, 2800k, 3500k, ect.
Plants metabolic growth rates and elemental needs/use, are dependent on these points within the color spectrum. As such, cal/mag requirements increase with an increasing metabolic rate.

***Copy and pasted below from Google***
The peak wavelengths for different types of chlorophyll are:

• Chlorophyll a: 430 nm and 664 nm
• Chlorophyll b: 460 nm and 647 nm
• Chlorophyll c1: 442 nm and 630 nm
• Chlorophyll c2: 444 nm and 630 nm
• Chlorophyll d: 401 nm, 455 nm, and 696 nm

Chlorophyll a absorbs light most in the red and blue regions of the visible spectrum, which is why photosynthesis is most rapid in these colors.


The ratio of chlorophyll fluorescence emission can be used to measure chlorophyll content. The Dualex is an optical sensor that can measure chlorophyll content in leaves in real time. Spectrometers can also be used to measure chlorophyll content in leaves.

I grow in coco my tap water is less than 100ppm it doesn't trigger the meter but I've not needed calmag with hid or led lights.

I've noticed there's more of a demand for nutrient with led compared to hid but no need for cal/mag.

Magnesium plays a critical role in photosynthesis by being a central component of the chlorophyll molecule, which is essential for capturing sunlight energy, and also acts as a cofactor for key enzymes involved in the carbon fixation process, particularly the enzyme Rubisco; in cellular respiration, magnesium is important as a cofactor for various enzymes involved in the electron transport chain and ATP synthesis, supporting overall energy production within the cell.
Key points about magnesium's role in photosynthesis:
Chlorophyll structure:
Magnesium sits at the center of the chlorophyll molecule, allowing it to absorb light energy efficiently for photosynthesis.
Rubisco activation:
Magnesium is necessary for the activation and proper function of the enzyme Rubisco, which is crucial for carbon dioxide fixation during photosynthesis.
Enzyme cofactor:
Magnesium acts as a cofactor for several other enzymes involved in photosynthetic processes.
Key points about magnesium's role in cellular respiration:
ATP synthesis:
Magnesium is required for the proper functioning of ATP synthase, an enzyme complex responsible for generating ATP, the cell's primary energy currency.
Enzyme regulation:
Magnesium acts as a cofactor for various enzymes involved in the electron transport chain within the mitochondria, which is essential for oxidative phosphorylation.
Maintaining stability:
Magnesium contributes to the structural stability of important cellular components like ribosomes and membranes, indirectly supporting cellular respiration processes.

Calcium is an essential nutrient for plant growth and development, and plays a number of roles in plants, including:
Cell structure: Calcium is a key component of cell walls and membranes, which helps strengthen the plant's structure.
Cell division and elongation: Calcium is involved in cell division and elongation.
Cell signaling: Calcium acts as a second messenger in many physiological and developmental processes, including the plant's response to biotic stress.
Enzyme activation: Calcium activates several plant enzyme systems.
Nutrient uptake: Calcium stimulates the uptake of other nutrients.
Root growth: Calcium improves root growth conditions.
Microbial activity: Calcium stimulates microbial activity, which is important for soil health and fertility.
Nitrogen fixation: Calcium helps nitrogen-fixing bacteria capture atmospheric nitrogen gas and convert it into a form plants can use.