Why do people say Calsium & Magnesium is `required` for LED -grows ?

I´ ve seen in several threads that people use and recommend calmag for LED -grows. Are you all just purporting a claim made by someone or are there more concrete studies?

I´m trying to wrap my head around an idea of a few wavelengths that are mostly used (660,630,460,430...) Having a special need for the two nutrients to properly keep the growth process going, in contrast to an HPS -grow where that wouldn´t be important. Or does it just have something to do about lower room and soil temperatures that calmag aids the use of nutrients? Maybe it´s a myth originating from old poor quality lights and given as an explanation for poor results by the light seller?

Im going to get some powdery dolomite lime anyway for soilpots. As it´s great in many ways. But I do appreciate point of views of RIU -members as there is much better info here than any other forum I think. Thanks!

I've never heard that is it required. I have heard that LED light doesn't really penetrate very deep into the canopy though. It sounds odd that one would have to supplement with CaliMag solely because of the lighting scheme. My first guess is that many LED growers might use RO since they have the coin to spend on LED, why not get an RO... then because of the RO they need CaliMag.... I'd love to hear what people say about this though.

I think cal and mag are required for any grow if you want strong healthy plants.

CaliMag is important because they are two micro nutrients, which aid in the transportation and use of Macro nutrients. AKA, they help in the use of the important N, P, K. They are important for every grow and every plant, but typically tap water has some Calcium and Magnesium so supplementation is not necessary.

Chronic Indica said:

I think cal and mag are required for any grow if you want strong healthy plants.

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Yes.

Flowering cannabis plants in particular use lots of these two nutrients, and its easy to deplete your medium without supplementing them.

You can look up what the CEC of your medium is before you buy them to see how much Ca/Mg you need to suppliment with/how often.

Ok. I agree that Ca & Mg are important for a healthy plant.

Dolomite lime (CaMg)(CO[SUB]3[/SUB])[SUB]2 [/SUB]In its powdery form is quickly soluble and long lasting.
[SUB]It also balances the ph as it´s ph is about 7 so when Its used in soil it works both as an -up and -down. And good ph makes nutrients available for plants.

I´ve just noticed that LED users specifically seem to value them more than growers with different lights. Thats why I said `requires` , although I mean is `deemed cruzial for a successful ledgrow` apparently. Thanks for replies.

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i was growing using hps then turned to blackstar 240's led and my plants went from dark green to yellow and the leaves just burning away under the led, the nutes i was using was biobizz grow and bloom and it just wont cut it for led, ive bought calmag and an revive which i am hoping will fix the problem, i agree theres somthing different under led and if your using good nutes you may not see any difference but if you were using run of the mill nutes that gives ok results under hps you could be in trouble using them nutes under led

I think I know where op is coming from. I was told by led light guys to get calmag of some sort. He didn't say a specific brand so he wasn't trying to sell me it. I think reading from various posts it helps with all grower but for led users, the plant uses light to turn into energy and food. Maybe the uv or the wavelengths led give require it more than hps? Op asking why it is more important to use a calmag supplement for led compared to hps that don't need it as much. I know led produce more frost and crystals so maybe that's a contribute to the factor?

Why???
Simple... urban legend.
Cal/Mag is used in almost all grows.

Yea, it makes very little sense why nutrients, especially micro nutes, would be needed in higher doses than in a similar medium with just differing lighting schemes.

if i might add my two cents i like adding egg shell to my grows it has calcium also helps control ph. the cal/mag is just extra precautions, its rare to see a calcium deficiency but ive actually seen a couple where calcium was the problem that was overlooked alot. Some people have the dolomite or limestone [and whatever else store bought soil uses for Ca] but some using hydro grows or even soil grows never even mention putting calcium into their grow. and more times than not they are the ones that end up with a Ca deficiency. So is it required? no, does it help lessen the playing field of problems later on? of course.

Ringsixty said:

Why???
Simple... urban legend.
Cal/Mag is used in almost all grows.

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Yeah. I think this comes from people who first started growing with LED and would constantly over-water their plants. This would probably lockout calcium and what's the answer to what appears to be a calcium deficiency? Probably started that way, but that's just my theory. I've been growing for about a year with LEDs, and have never seen a Cal/Mag problem. Then again I always use lime so... .

My very first grow is under LED for flower, but I'm also using RO water (my tap is full of junk, ph 8.0). Don't know if there is any relation, though I did buy Cal-Mag supplement and use it every watering (about every 5 days) and my plant that was showing some potential deficiencies is doing much better. But again, it could be the RO water.

FYI, I do use calcitic lime, can't find dolomitic pulverized.

RO water- 0ppm/EC/TDS. If a human even drinks nothing but RO water all day they will actually become severely dehydrated because there are no micronutrients, nothing in the water besides hydrogen and oxygen. It is very important to supplement or plan ahead with your mix if you use RO water.

hölynpöly;7348917 said:

Ok. I agree that Ca & Mg are important for a healthy plant.

Dolomite lime (CaMg)(CO[SUB]3[/SUB])[SUB]2 [/SUB]In its powdery form is quickly soluble and long lasting.
[SUB]It also balances the ph as it´s ph is about 7 so when Its used in soil it works both as an -up and -down. And good ph makes nutrients available for plants.

I´ve just noticed that LED users specifically seem to value them more than growers with different lights. Thats why I said `requires` , although I mean is `deemed cruzial for a successful ledgrow` apparently. Thanks for replies.

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Never used the stuff before myself, been using tap up until a couple months back. I'm doing a comparison with two different rooms/plants (actually 4 plants, 2 in each room), the details I won't bother with since I'm addressing this thread and will comment on my personal experience with cal/mag def under LED. I couldn't tell you why but I can say its true, if you're growing under LED then you need to supplement cal/mag . My comparison involves all the same feeding schedule, I switched to RO in the middle of the grow, the plants under the HPS didn't show much or any sign of cal/mag def but the ones under the LED showed severe def(crispy leaves and all), I found all this not long ago (cal/mag def is certainly hard to see under LED but I let it go even further than I should have)and have been supplementing in both rooms.

Some misinformation here. I do not know any particular 'studies' that say this, only my experience from being an HID grower who has switched to all LED.

Cal-Mag is *ESSENTIAL*. No, it is NOT essential to HID growing. I have never, EVER bought or used a cal-mag supplement prior to growing with LEDs. The only time I've ever had a cal-mag deficiency ever is from nute lockout due to poor pH or overwatering under my HIDs. Under LED, *every single plant* needs cal-mag supplementation or they WILL get first magnesium deficiency, then calcium. My plants that are in supersoil with calcium and magnesium sources in the soil do not get calcium deficiencies, but they do get some magnesium deficiency -- far less than plants not in supersoil with no added cal-mag in the soil. In veg, you will not need much if any cal-mag. In flower, you will need to supplement every or almost every watering unless you have it supplemented in the soil. I don't know anything about the reason why this is. All I know is that for me, personally, with my experience of several grows under HID and this one under LED -- Cal-Mag is ESSENTIAL unless you are properly supplementing in soil.

I have added crab shell meal and extra epsom salt to my soils and am going to do so from the start for my next batch of super soil, so I expect to rarely if at all need cal-mag supplementation in the water... but it is for sure needed. Also, the 'bleaching' at the top of plants under LEDs is not bleaching as far as I can tell but mg deficiency due to not getting enough in those areas that is showing it. If you look at the yellow pattern in the leaf it is mg deficiency. Ca deficiency is rarer than mg but definitely happens in soils without it added in flower.

Moving plants farther away from the lights appears to help. Even if you don't see bleaching at the top though you will often see it at the bottom leaves... but it is not the general yellowing of flower and the leaves ultimately look burnt. Moving lights up will not prevent it at the bottom, only at the top.

Ringsixty said:

Why???
Simple... urban legend.
Cal/Mag is used in almost all grows.

Click to expand...

Lack of personal experience possibly, I learned this is true on my first LED grow, how many you done without cal/mag? I've done loads of grows without supplementing under HPS or t5 but you put your shit under an LED panel and you damn well better supplement cal/mag.

^^^^ truth.

I am seeing LED bleaching for the first time and the white growth looks like a lack of chlorophyl, which I think is an Iron deficiency (chlorosis?)
Does Cal/Mag have Iron in it?