Mag deficiency, or overwatered coco?

[Kazooey59]

I am not sure it is a symptom? the coloration crosses the veins which is unusual in a magnesium lock out. It may be a little bit of variegation which is genetic. The plant is young and they often show strange growth early. That said are you fertigating properly? Start no sooner than two hours prior to lights on and stop fertigating two hours prior to lights out. Fertigate to a minimum of 20% run off to waste every day you fertigate. If you are doing recirculating recirculate the volume of your reservoir each day and watch the PPM when it drops by 100 - 150 PPM change the reservoir. PH to 6.8 as often as you can. The ok range is 5.5 to 6.1

Fertigation is rather simple, as I'm running them on 24/0 like always, which never caused problems to me. I fertigate them twice a day usually, mid-day and evening, always 30ml back when they were in 16oz cups, always til runoff as 30ml was the sweet spot. Now in the final pots they didn't get watered, just transplanted into pre-fertigated coco with their usual feeding schedule, then transplanted. I let them dry out for 3-4 days after transplant, and then start feeding daily again, just normal top feeding til runoff until they're ready for the autopot system

I've never seen variegation like this though, it seems to spread at growth that becomes slightly older over time, slowly burning through the leaf material. I'll take some closer pics for you guys:

Does this look like variegation? I feel like on some leaves it does resemble a magnesium deficiency early on, but the later progression looks nothing like magnesium to me. It's weird.

Here are the "early" signs, just a hint of yellowing on the leaf material, similar to early mag:

 

[Mañ'O'Green]

Well I don't believe in growing 24/0. You are not fertigating coco correctly to maximize it's value. Letting any media "dry out" is a bad idea. It just kills roots and microbes, causes hydrophobic pockets.

 

[Kazooey59]

Well I don't believe in growing 24/0. You are not fertigating coco correctly to maximize it's value. Letting any media "dry out" is a bad idea. It just kills roots and microbes, causes hydrophobic pockets.

No worries, they were fertigated 2 times a day.

I started this grow by pre-watering the solocups, then letting the pre-germinated seeds sprout. They weren't watered for around 2-3 days after planting, and then got 1 daily fertigation for 3-4 days, and then 2 fertigations per day til runoff, always raising EC/PPM until I hit my max schedule.

I only let them dry out for a few days (2-3) after transplant to let them grab onto the substrate, after which I go back to fertigating as usual. The 24/0 is just because they're autos. My current other Autoflower enjoys 24/0 a lot, taking up almost 1/4 of the 4x4 tent while in early early preflower, no stretch yet:

As mentioned above, they do get treated the way you prefer, even though some criticized me to hell for watering plants in coco twice a day, I kept it that way. The reason I'm coming here is because some show symptoms I've never seen before, and I wanted to know if anyone has an idea as to what's going on there, especially because it's only on two of the same strain.

Is there no one who has seen a symptom like I've shown above in the thread? I can't be the only one, I ain't that special

 

[BII]

This is what I ws taught by @Mañ'O'Green which I trust wholeheartedly plus I've been doing it for a while now and my plants are better. I like tothink there little more to it then just "bro science"


The history of why I invented stabilizing RO. When I first started using RO It did all manor of weird PH shit to my reservoir when I added it to bring the PPM down in a nutrient mix to the range I wanted. I used RO because it added only water to the mix. But it took copious amounts of up or down to keep PH in range. You know that PH+ Nitric Acid adds nitrogen, PH+ Phosphoric Acid adds Phosphorus to your nutrient mix. When you use large amounts it will change your nutrient balance. Keep in mind I am in hydro and my PPMs would change by as much as 75PPM. This was not desirable. Then I learned that RO water is hungry and will pull Co² out of the air and drop the PH to 5.5 or lower. I read somewhere that adding some base ions would mitigate this action. It can be any metal ion. I started adding a little cal-mag to the RO and Bota Boom Bota Bang it stop hijacking my reservoir PH. Then I discovered that everything mixed better without any precipitation I could see if I used this "buffered" RO. The reason I used 50 PPM of Cal_mag was because that was the lowest number my EC pen could read. Not all Cal_mags are made the same but most are calcium nitrate and Mg nitrate and maybe some iron once again a source of Nitrogen I don't want. Hence my choice of Soluble Gypsum which is Ca and Sulfur, Epsom Salt is Mg and Sulfur. Cannabis can tolerate a lot of Sulfur way more than you are likely to get in any nutrient line. I settled on .3g Soluble Gypsum and .3g Ag Epsom Salt per gallon of RO that gets me close to that 50PPM mark that most meters can read. It works well for me so I teach it.

So you add cal-mag to stabilize the pH of your reservoir, not because the plants need the amount you're feeding. But is adding metals ion/salts needed say if growing in coco and feeding freshly mixed nutes (not using a reservoir)?

There are some cal-mag supplements that minimize the N/nitrates they deliver. CALiMAGic, a very popular brand, is 1-0-0 with iron. I vaguely recall the Ca/Mg ions are complexed with large-chain carbohydrates? For comparison, Adv. Nutrients' Cal Mag Xtra is 4-0-0.

 

[Mañ'O'Green]

So you add cal-mag to stabilize the pH of your reservoir, not because the plants need the amount you're feeding. But is adding metals ion/salts needed say if growing in coco and feeding freshly mixed nutes (not using a reservoir)?

There are some cal-mag supplements that minimize the N/nitrates they deliver. CALiMAGic, a very popular brand, is 1-0-0 with iron. I vaguely recall the Ca/Mg ions are complexed with large-chain carbohydrates? For comparison, Adv. Nutrients' Cal Mag Xtra is 4-0-0.

IMPO Yes, RO water that is exposed to air will gain a low PH if not buffered it can go below 5.5 and you do not want to be fertigating with that. If you Buffer RO before it is exposed to air you will be able to make small adjustments for PH and the fluctuations will be slower. It is not a PH panacea. I still monitor my PH often many times a day. I use water soluble gypsum and AG Epsom salt in my nutrient system. Feel free to use what ever source you want, just count all your inputs to stay in balance.

 

[Kazooey59]

Hey guys, small update from Canna themselves (translated from German to English):

"Basically, we recommend water with an EC of 0.4 and not pure reverse osmosis (RO) water. This is because RO contains no pH buffer, and coco also does not. Without a pH buffer, the pH level can be subject to extreme fluctuations (one drop of alkali/acid and the pH goes to 8/4). Therefore, it is best to mix tap water (TW) with RO. Either to an EC of 0.4 or, if the water quality is very poor, to an EC of 0.2 and then raise it to 0.4 with a CalMag agent"

So if I understood correctly, I should NOT use pure RO water and raise EC to 0.4 with their calmag agent? I don't really understand why I shouldn't do that, as I just add the minerals back into the RO water with their calmag agent. Maybe they didn't understand correctly? Or is it really not the right way to fully add 0.4EC with just calmag?

I could cut my RO water with 1/4 tap, I would have an EC of 0.15 then (pre calmag + NPK nutrients), and a final PH after nutrients at 6.1, rather than 4.6PH final with pure RO water, in which case I'd add Canna PH+ to the correct PH.

Any ideas? are my plants showing these symptoms because I'm using pure RO water with calmag until I'm at 0.4EC? I thought this is completely normal behavior with RO. I'm totally new to RO / Coco stuff, so I can just blurp this stuff out of basic experience with other grows

 

[BII]

@Mañ'O'Green: But on the other hand, aren't there a good number of popular base nutrients that recommend or work best with 0 ppm RO/DI starting water? The pH Perfect and other Adv. Nutrients base nutes recommend lowest ppm starting water; and their mainstream regimens don't include any Ca/Mg supplementation. GreenLeaf doesn't recommend any pre-buffering or adding cal-mag to MegaCrop (at least the 2-part version I'm using). Don't base nutrient products contain enough salts to buffer ('stabilize') RO water?

So even if freshly mixing and feeding nutrients (at an acceptable end-of-mixing pH), no reservoir used, one should pre-buffer RO water? Ideally to what ppm/EC? Is it best to prevent RO system output from exposure to air, collect it using a closed system, and pre-buffer that?
[For ex., I grow in 5-7 gallon bags of coco/perlite, feed freshly mixed MegaCrop 2-part with minimal supplements starting with RO/DI water (generally left sitting unsealed for about a day), and never pre-buffer or add cal-mag (maybe 1x/grow). Should I be pre-buffering the RO/DI water I use?]

 

[Lil Dab]

if I understood correctly, I should NOT use pure RO water and raise EC to 0.4 with their calmag agent? I don't really understand why I shouldn't do that, as I just add the minerals back into the RO water with their calmag agent. Maybe they didn't understand correctly? Or is it really not the right way to fully add 0.4EC with just calmag?

I could cut my RO water with 1/4 tap, I would have an EC of 0.15 then (pre calmag + NPK nutrients), and a final PH after nutrients at 6.1, rather than 4.6PH final with pure RO water, in which case I'd add Canna PH+ to the correct PH.

I’ve done it both ways and both work fine using pure RO then buffed or cutting tap with RO water either but if you using the tap water no need to add the pre calmag just one or the other.

If it were me I would cut my starting ppm/EC in half. I always thought 150-200 ppm was max for starting ppm if my tap water was that low I’d just use it but mine runs near 400 ppm all year. So I use RO with 50-100 starting ppm

But if all your other plants and past grows have been fine then maybe it’s just a weirdo strain?

 

[BII]

I’ve done it both ways and both work fine using pure RO then buffed or cutting tap with RO water either but if you using the tap water no need to add the pre calmag just one or the other.

If it were me I would cut my starting ppm/EC in half. I always thought 150-200 ppm was max for starting ppm if my tap water was that low I’d just use it but mine runs near 400 ppm all year. So I use RO with 50-100 starting ppm

But if all your other plants and past grows have been fine then maybe it’s just a weirdo strain?

I don't notice any problem from not pre-buffering my RO/DI feed water (with coco/perlite). I see no need to adulterate my starting water with salts that neither the plants nor media need and that are not recommended by my base nutrient manufacturer.

 

[Kazooey59]

It's sadly still spreading everywhere now, even the big healthy one. I gave them a dry period between each watering now (around 30% dryback), and it's still happening.

Currently cutting my RO water with tapwater at 25% which gives me a starting PPM of 80 / EC 0.16, which I then raise to 0.4 as recommended by Canna as per second email:

"Well, that is somewhat correct but unfortunately not entirely. CalMag serves as a Ca/Mg buffer, but it is unfortunately not sufficient for a stable pH buffer. Carbonates are particularly important for this, and getting them into the water is unfortunately not that simple. The good news is that you get them virtually for free with your tap water.

No matter how old your pipes are, you don't need to worry. Even with lead pipes, stagnant water is the biggest problem, but it is sufficient to let the water run for a bit in the morning before using it.

In any case, it is best to find out about the water quality from your waterworks or simply measure the EC and pH. Then, it is best to dilute the water to an EC of 0.2 and raise it to 0.4 with CalMag. This way, you have enough carbonates for a good pH buffer and still very pure water."

Just following the directions of Canna now. Sadly, without any success. It keeps worsening, and appearing on more and more leaves. I'm absolutely clueless, especially because this already started in the solo cups, which always got more than enough runoff to not cause any lockouts.

FYI - These leaves are wet because I did an epsom salt foliar at 1.6g/1L, calculated down from the usual 1tbsp/1gal foliar feeding of epsom salt. It's my last attempt to fix this, as I don't have any other ideas. Lights were out while the plants dried up.

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