Rusty leaves and yellowing plants on a first(ish) grow. :(

[Cat Lady Nursery]

Hey there. I'm Link. This is my first post. This is my first(ish) grow. My gf usually does this stoof, but she's been busy with work lately, so I'm taking the reigns on the diagnosis.

Narcotic Kush AF

Anyways... All three plants are identical as far as germ to pot process, strain, water schedule, etc.. All three are in a 3x3x6 grow tent, 5G pots each. Average Humidity 30-50 Average temp 72-77
Using Biothrive Grow and Bloom, as well as CalMag.

Even though all three were cared for the exact same, Plant 'A' started the rust leaves a few [4?] days ago. 'B' is bushier and shorter than the others, lol. 'C' is very yellow and now has the rust splotches as well.
Any advice would be wonderfully helpful!

<Plant A <Plant B < Plant C Tent with lights off/on.

 

[Druid]

Looks like you're 4 to 6 weeks into it. If you haven't changed your nutrient plan this looks an awful lot like magnesium deficiency looking at the rusty spots. What i'm missing for a absolute certain diagnosis on that though are the chlorosis symptoms. The very light green also looks like you're missing sulphur in your diet. May i suggest supplementing the calmag with some epsom salt for a bit. You can get it at any pharmacy for 5 bucks.

Are you using tap or RO water? And what's the ph of your nutrient solution?

 

[Cat Lady Nursery]

Germ 8 Sep / Plant 11 Sep
We used distilled water, and I know she adjusts the PH levels of the water. Not sure the level. 7-7.5? 6-6.5? Something like that.
Right now we're using 2TB of Grow, 8TB of Bloom, and 7TB of CalMag

 

[IndicaIVoz]

your suffering a cal-mag (or just mag) def and possible rust fungus issues. scratch the rust fungus its just a calmag issue .use cal-mag supp. common under led lights. hope this helps.

 

[Druid]

your suffering a cal-mag (or just mag) def and possible rust fungus issues. scratch the rust fungus its just a calmag issue .use cal-mag supp. common under led lights. hope this helps.

Calcium deficiencies show themselves in the first 2 weeks starting at the oldest leaves. Magnesium deficiencies around 4 to 6 weeks and start at the oldest leaves closest to the new growth. Calmag would stop this issue but look at the shade of his leaves. They are way less saturated than they are supposed to be => sulphur deficiency. Hence my suggestion for Magnesium sulphate (epsom salt).

I am quite new to this specific plant but have noticed a few peculiar things when I was looking at fertilizers(for cannabis) online. Many manufacturers like to leave out zink and sulphur from their mixes. While I like general hydroponics for their maxi bloom nutes they don't give out their component breakdowns and I can't say it's not the cause. Since I wawter with tap water and supplement epsum salt i don't get this but since he uses demineralized water i'm sure you can see why I reason this way.

 

[IndicaIVoz]

Calcium deficiencies show themselves in the first 2 weeks starting at the oldest leaves. Magnesium deficiencies around 4 to 6 weeks and start at the oldest leaves closest to the new growth. Calmag would stop this issue but look at the shade of his leaves. They are way less saturated than they are supposed to be => sulphur deficiency. Hence my suggestion for Magnesium sulphate (epsom salt).

I am quite new to this specific plant but have noticed a few peculiar things when I was looking at fertilizers(for cannabis) online. Many manufacturers like to leave out zink and sulphur from their mixes. While I like general hydroponics for their maxi bloom nutes they don't give out their component breakdowns and I can't say it's not the cause. Since I wawter with tap water and supplement epsum salt i don't get this but since he uses demineralized water i'm sure you can see why I reason this way.

Yup i completly understand where your comming from however your forgetting one thing..calmag is usually iron chelated anyhow.
edit.sorry you said sulfur ..anyway i would myself go with just the calmag in this instance myself because of the cal def caused by the leds n most cases.however epsons is very good also.so i see your point IF it wasnt for the leds.

 

[IndicaIVoz]

Either one will do. since your already adding cal mag it might be best to stick with the reasons @Druid suggested go with epsoms. i agree after looking again. ty @Druid

 

[Cat Lady Nursery]

GF here. Level is 6.0-6.5. I have been increasing the calmag as much as I can without nut burn. At this point Im desperate lol. However, I had no idea about sulphur!!!! What will epsom salt do? I have never heard of using it before.

 

[Druid]

Yup i completly understand where your comming from however your forgetting one thing..calmag is usually iron chelated anyhow.
edit.sorry you said sulfur ..anyway i would myself go with just the calmag in this instance myself because of the cal def caused by the leds n most cases.however epsons is very good also.so i see your point IF it wasnt for the leds.

Yeah that's another oddity about these symptoms. It looks like magnesium deficiencies.. but those usually come with some yellow clouding ala chlorosis and I don't see that here. I do very much appreciate you giving a second opinion since I'm still learning this plant. Now the reasons for magnesium lockout can be that the substrate or solution are too sour or there is excess calcium. calcium can be locked out by ammonium, kalium or manesium but since his RH seems to be in a good range it's less likely to be the problem.
My suggestion would be to flush with a 2% magnesium sulphate solution.

Ah it's awesome to be able to get nerdy about plants.. if i talk about that stuff to normal people they just go blank

 

[IndicaIVoz]

Epsoms can be sprayed on for quick absorption and works very fast it can be added to feed but watch the ppms its very heavy