K def? Mg def? Ca tox? something else?

Sick Plants & Problems
1

Hello Everyone, this is end of week 3 in flower. Some bottom leaves are partially yellowing - in what seems to be a K def? which doesnt make much sense cus I feed 20-10-20 650ppm on average with low 6 ph (soilless)- with added silica and ph down ( P ).

maybe Ma def?

Would really appreciate any input :slight_smile:

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I also amend the medium with gypsum, I sprinkled a little more when going into flower… but nothing that would cause a toxicity as far as i understand.

My journal is here

but I can summarize

Medium:

45% PEAT
45% VERMICULITE
10% PERLITE

  • Added
    Dolomitic Lime at 40g per 28.3L of medium and
    Gypsum at 10g per 28.3L of medium (I have added about 15 grams per 28 liters)

Nutrient: I try to water when container is light

1.2 - 1.3 EC (600-670ppm) 20-10-20 Peter’s

Tap Water - 120ppm

  • Added
    light dose Armor SI 2 ml per 10 L - start 2 weeks after sow.

PH
low 6

VPD:
has been maintained at about 1 to 1.2 with minor peaks out of that range.

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2

A few yellows is normal but I think yours wants nitrogen

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3

Is the 1.2-1.3ec including your tap water?

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4

Thanks! but at 20-10-20? I thought nitrogen would be covered.

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5

yup, with tap

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6

Your feed looks something like this…
At this stage I drop my N and increase PK. Also there is hardly no Mg in your 20-10-20

I’m unable to guess the amount of Ca with gypsum as it’s in your medium. I think 1g in 1 gallon is around 60ppm.

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At this stage I’m feeding loads of PK with N reduced to 80-90ppm as I ride that till week 8 then drop it even further… I would be leaning towards Mg as I don’t see any in your feed.

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7

Thank you so much!

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8

Someone else may have some input. The lime your adding has Mg though…not sure of the amount there.

I’m hydro so I’m mixing these with my feed so I’m not questioning myself lol

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9

I will wait if anyone has any other input

…in the meanwhile ill order epsom salts and calmag (its two plants giving the issue) so the plan will be to try epsom in one and calmag on the other. See how it goes.

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10

Maybe overwatering but I’m not 100

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11

I would go for Magnesium deficiency … hum|nullxnull

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12

Maybe there’s already too much :frowning: after reading this now I don’t know what to think … icon_e_confused|nullxnull

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13

Theres a good article on Growweedeasy.com that covers all leaf abnormalities/nutrient problems.

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14

Thanks, I also visit the diagnosis tool, that why I was between Mg and K def.

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15

Great information.

So the unknown for you @the_bot is how much Ca/Mg/S is in your pot.

I just went down the rabbit hole with gypsum (can’t use it in my setup) but she will add a ton of Sulphur also.

@corgitron have you run into anything similar at all? I know you’re not always supplying gypsum.

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16

I added about 5 mg more than reccommended of gypsum to the mix per 29L. not sure f that would cause a toxicity.

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17

What was the initial amount amended to the 29L.

That method he mentioned a 10% tolerance for gypsum. If you think it’s more than that you would be suspecting what @George pointed out and you could be looking at excess.

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18

the original amount is 10mg per 29 L, I added 15mg per 29L. Although Gypsum is Calcium and Sulfur, the excess would not be of Mg in that case

My Mg source was Dolomitic Lime at 40gr per 29L which is what I used.

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19

Sorry. So yes could be excess Ca. Sulphur not sure…have never seen a max limit yet…and I know a few that give plenty.

So Ca locks out K, Mg, Fe and Mn.

So the additional 5g would put you over his 10% margin for error.

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20

Oh wait, im a stoner… i remember now why i added extra gypsum. Bugbees tap water has higher ppm than mine. mine is 120ppm - and since i dont know how much of it is Ca being in the limit of soft, i went ahead and did some fantasy math in my head and came up with that increase… though, wether it is correct… i couldnt say lol.

if ts Ca tox im kinda screwed since it was amended. i could try to replace some of the medium but id be afraid of doing more damage than anything.

I could try the epsom salt in one and see if it stops the chlorasis. if it doesnt, i guess il have to ride it out and use less gypsum next time.

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