Unstoppable mag deficiency under LED

[dirty budster]

I figured it was time for an update. I gave them another feeding 5 days ago with a full dose of veg nutes and a double dose of cal-mag. I watered them until run-off. The run-off was a bit high at 6.8-6.9 so I will be lowering the pH of the feed next time. After 2 days I noticed some clawing on the fan leaves and I was worried I had overdone it with the N but 1-2 days later the clawing stopped. I noticed quite some new growth, especially the side shoots have started taking off so I think I'm heading in the right direction. They're also starting to turn a darker shade of green. I'm still seeing signs of mag def on the new growth but much less pronounced than before.

They're starting to dry out again so I will give them another feeding tomorrow. Since it looks like I'm dealing with a pure mag deficiency so far (I haven't seen any signs of cal def) I will try something a bit different. Instead of a double dose of cal-mag I will go down to a single dose and add 1 tsp of epsom salt per gallon to increase the mag ratio. I'm starting to wonder if the mag is getting locked out by too much calcium. They will also be getting another full dose of veg nutes. Is 1 tsp per gallon a reasonable amount of epsom salt? I've never used it for watering before only foliar feeds. If you have any other suggestions I would be happy to hear them.

Here's a picture from today, day 36. I'm hoping to let them recover a bit more and then flip to 12/12 within a week, hopefully.

 

[Torched]

Have you tried foliar feeding some Epsom salt? Should be faster acting and won't mess with your soil or any potential lockouts.

 

[az2000]

Here's a picture from today, day 36.

I think they look pretty good. I agree with torched about foliar feeding. But, (as mentioned by someone previous in this thread) the high ph shouldn't lockout magnesium. I'd foliar feed nitrogen in some form. AK Fish emulsion, or household ammonia. Maybe some AK Kelp for other nutes maybe locked out from high ph?

 

[dirty budster]

I tried foliar feeding but I didn't have a lot of success with it. I never really saw much improvement. It might have slowed down the progression a bit. I was foliar feeding with 1/3 veg nutes and 1 tsp/litre epsom salt with a pH around 6.5. I only saw some real improvement by adding larger amounts of cal-mag to the regular feed.

 

[Waira]

:Sharing One:Hi Budster- ...not surprised the run-off was that alkaline, with all the Ca-Mg that's going into there! You have to be careful not to overdo it with the Ca input, as this can potentially interfere with other nutes' uptake,...therefore, a good idea with the epsoms, and better still, don't give up on foliar spraying-- it's the fastest way into the plant, puts the nute's right where they need to be right off the bat, and if there's any kind of issue with the soil, foliar takes that out of the uptake equation; What's key to foliar spraying is using a water spreader/wetting agent; this stuff takes the surface tension out of the solution you're spraying, so it sticks and spreads more evenly, instead of just beading up.... spray bottoms and tops of leaves as well; point is, simply put, is the more surface area covered = more absorbed! Takes a couple days only to see results usually,...trust me!-- Az' and Torched too- :thumbs: *** I don't think there is a N issue, or there'd be far more yellowing on the bottom leaves,... N is very mobile, and it's from here that the plant will draw reserves first,.... *** Also factoring in potentially is pheno' quirks; Seem's nearly every grow I have, at least one strain has a pheno' that's weird about Ca and/or Mg,...LOL! right now, I have 4 Grape Hash plants unsexed (photo's), 2 phenos, and as usual one pheno' looks like they're starving for something-- paler, kinda blotchy, course texture to leaf surface, and a significantly different build,...but it's a lie-- LOL! -they're just as big and equally vigorous as their seed mates, and refuse to color up despite several treatment with both Ca-Mg and a mixed metal supplement spray! (GreenAll brand, killer stuff: Fe Mn, Cu, Zn + 2-0-0) ... Anyway, do reconsider foliar,... soon, when bloom begins, this defc. is very likely to really flare up, and fast, so having foliar in your skill-belt will pay off nicely!

 

[Gonzo]

Budster, you had put a lot of dolomite lime in there at the beginning.
Have you thought about DL beeing your persistent trouble? It lifts ph wildly in your case and is able to make lockouts when abundant as I read?
In Plagron GM you do not want anything to interfere with stable ph which Plagron is able to mantain and that is 6,5 or around, not far away if you constantly water with 6,5.
How much have you put in (grams or volume but not in tsp, tbsp)?

Waira, I am surprised you do not mention DL in your post, your opinion about it would be precious.

 

[dirty budster]

:Sharing One:Hi Budster- ...not surprised the run-off was that alkaline, with all the Ca-Mg that's going into there! You have to be careful not to overdo it with the Ca input, as this can potentially interfere with other nutes' uptake,...therefore, a good idea with the epsoms, and better still, don't give up on foliar spraying-- it's the fastest way into the plant, puts the nute's right where they need to be right off the bat, and if there's any kind of issue with the soil, foliar takes that out of the uptake equation; What's key to foliar spraying is using a water spreader/wetting agent; this stuff takes the surface tension out of the solution you're spraying, so it sticks and spreads more evenly, instead of just beading up.... spray bottoms and tops of leaves as well; point is, simply put, is the more surface area covered = more absorbed! Takes a couple days only to see results usually,...trust me!-- Az' and Torched too- :thumbs: *** I don't think there is a N issue, or there'd be far more yellowing on the bottom leaves,... N is very mobile, and it's from here that the plant will draw reserves first,.... *** Also factoring in potentially is pheno' quirks; Seem's nearly every grow I have, at least one strain has a pheno' that's weird about Ca and/or Mg,...LOL! right now, I have 4 Grape Hash plants unsexed (photo's), 2 phenos, and as usual one pheno' looks like they're starving for something-- paler, kinda blotchy, course texture to leaf surface, and a significantly different build,...but it's a lie-- LOL! -they're just as big and equally vigorous as their seed mates, and refuse to color up despite several treatment with both Ca-Mg and a mixed metal supplement spray! (GreenAll brand, killer stuff: Fe Mn, Cu, Zn + 2-0-0) ... Anyway, do reconsider foliar,... soon, when bloom begins, this defc. is very likely to really flare up, and fast, so having foliar in your skill-belt will pay off nicely!

Thanks for the input Waira! Yeah, I wasn't happy with the amount of cal-mag I had to use so I switched to epsom salts. If it works out with the epsom salt I will use them from the beggining next grow. I also suspect that I might have too much calcium and that's why I see Mg def so early, not sure yet though. I did use a small amount of soap to break the surface tension and I could see that it spread pretty evenly across the leaves. I'll give it another try, I mixed up a bottle with 1/3 veg nutes and I will foliar feed them with that. There has been quite a lot of growth in the 2 days since the watering so they seem to like it. Still too early to say if the mag def is solved, it usually takes a few days until it shows up on the new growth. The side shoots are still a bit pale looking so I think they could use more N.
I'm having trouble keeping up with the feeding because they're still taking too long to dry out so I'm not able to water as often as I would like. I hope that improves now that they're a bit bigger. I think it might be time to flip them soon or I might run out of space. I have 0 experience with photos so I'm not sure how much growth to expect once I flip them. If they really get twice as big I have a feeling I will be playing snake with the main tops

Budster, you had put a lot of dolomite lime in there at the beginning.
Have you thought about DL beeing your persistent trouble? It lifts ph wildly in your case and is able to make lockouts when abundant as I read?
In Plagron GM you do not want anything to interfere with stable ph which Plagron is able to mantain and that is 6,5 or around, not far away if you constantly water with 6,5.
How much have you put in (grams or volume but not in tsp, tbsp)?

Waira, I am surprised you do not mention DL in your post, your opinion about it would be precious.

I added the dolomite lime this grow because I had mag issues last grow as well and I was hoping that would help during the first couple of weeks. It did raise the pH but didn't seem to do a whole lot for the mag def. I put in 30ml of DL per 6.5l pot. I read recommendations of 1-2 tbsp (15ml) per gallon of soil so 30 ml in 6.5l is slightly more than 1 tbsp/gallon. Another reason I used it was that the pH dropped at the end of the grow last time and I thought it might help a bit with that. I'm not so sure I will use it again.

Lastly, a picture from today, day 39:

 

[Waira]

.... yeah, dolomite is fairly slow acting/releasing, and the more course the grains are, the slower it is,...but the up side is, dolomite can't raise things above 7.0, and the more alkaline conditions are, the slower the release, and therefore less Mg is made available,... so, even though there's a source in there, under alkaline conditions, the dolomite alone may not be able to keep up with demand... all things considered, the pH currently isn't off enough to interfere with uptake of anything except Fe, and to a lesser degree, B and Mn; Mg is very robust in availability under alkaline conditions, like you have,... I see no signs of either Mg or Ca toxicity either,...*** Mg is fully mobile, so defc. will not show up first in newest growth, but lower down, from fans that are being tapped to support that new growth,... ditto for N- lowest leaves are usually the first to show signs; if there's a cause for pale color, it's Fe defc., which under alkaline- even 7.0- conditions goes lockout very quickly,... LOL! Again,a foliar spray will tune that up just fine if the soil is suboptimal pH! *** ....forgot to ask, and it's highly relevant- what water source are you using? RO, or dechlorinated tap?... A simple, easy and cheap pH down'er is white vinegar; add it to you nute solutions, maybe 1/4 tsp at a time, to ease the pH down,.... before I get technical, do you have an understanding of how buffering works in water, why RO is so susceptible to big pH changes, the role of hardness alkalinity if stabilizing pH, blah blah blah? *** Again, looking at the other minimally/non-affected plants, you just might have greedy Mg phenos',...another case in point: last year, I had 2 MoB's, different pheno's, and one had nearly constant Ca-Mg issues, going through easily 5x what her seed-mate did,... looked a bit ragged by the end, but the bud was superb!

>>> Gonzo- hey bud, what's up? :smoke: ...not sure what you mean,... you think too much dolomite went in initially? It's possible, but that call would depend largely on how acidic the soil was by itself,... I don't have info on Plagron, or it's pH and buffering agents,... what he did add was a typical recommended amount for general amendment purposes,... I don't think it was a cause of any defc. troubles here,... the alkaline conditions of the soil aren't an issue with Mg uptake; as for pH issues, see above....

 

[dirty budster]

Thanks for that Waira, that was an interesting read!

It's tricky to tell if there's still a Mg def on the older leaves since they've already been completely ravaged so I have to look a bit further up the plant. Interesting about the Iron deficiency, I didn't know that it could get locked out at pH 7.0 already. I added some cal-mag to the foliar feed as it contains some Iron as well, just in case. I'm a bit concerned about how bright green the new growth is but I will see if the foliar helps with that.

I'm using non-chlorinated tap water. It's usually around pH 7-8 initially and I've been using vinegar to bring it down to around 6.5, after adding the nutes of course. According to the water report it should contain 50ppm calcium and 10 ppm magnesium. Last feed I did at pH6.1 to try and bring the pH down a bit. I have a basic understanding of pH and buffering but I'm far from an expert

 

[Gonzo]

I added the dolomite lime this grow because I had mag issues last grow as well and I was hoping that would help during the first couple of weeks. It did raise the pH but didn't seem to do a whole lot for the mag def. I put in 30ml of DL per 6.5l pot. I read recommendations of 1-2 tbsp (15ml) per gallon of soil so 30 ml in 6.5l is slightly more than 1 tbsp/gallon. Another reason I used it was that the pH dropped at the end of the grow last time and I thought it might help a bit with that. I'm not so sure I will use it again.

I use GN06, hesi, rhizo and Plagron and I do not see any other reason for your troubles as DL. We both water with ph 6,5 water, you have troubles, I have wonderfull plants, all green. We do everything very similar, except I use only half teaspoon of DL in 18l of soil, just because I do not get proper calmag here around, and that is exactly 1/30 of what you had used.