Getting some 'blotchy' lowers 4th week in flower...Potassium issue or something else?

My details:
-2x Durban Poison (Dutch Passion) photos, 4th week of flower
-5g bags with ProMix HP+
-Feed/Water by Blumat Tropf system (drippers).
-MaxiBloom @ 3.5g per gallon (.7ish EC), GH Ca/Mg @ 5ml per gallon. Maxi is: 5/15/14
-Water is well water (.44ec), reservoir is pH'ed daily to 5.9 and drifts to 6.2.
-Temps are 75-85, and RH is 48-52%
-Lights are @ ~850umol (HLG Quantums).

Tops are pretty healthy and show no problems besides some tip-burn from before the installation of the Blumat system (a feed up towards 6.5g per gallon). Had a Ca issue a while back but have been adding 5ml per gallon and that seemed to ease things. Right now getting the start of some blotchy chlorosis on the lower/mid fans, and some small pinhead sized brown spotting...Would love to figure it out. Seems to point to P/K issues, but I'd love confirmation from the fine people here. Before this I'd done a bunch of runs of autos but this is my first Photo and with something closer to a full Sativa.

Here's what I'm seeing:



Here's what they look like over all:



And again, the tops, or budding areas seem pretty ok for now:



Diagnoses? Adjustments to my feed strength? Changes in my Ca/Mg use? I'm all ears, especially for those who are long-time growers.

Looks like your past deficiency is just showing in older fan leafs to me. Idk would need to see a picture from a week ago...

Magnesium deficiency

ProPheT 216 said:

Looks like your past deficiency is just showing in older fan leafs to me. Idk would need to see a picture from a week ago...

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These were taken back about a week and a half ago... somewhere in the May 10th or so range.

hotrodharley said:

Magnesium deficiency

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Thank you, as always. Add an additional bit of Epsom to my feed along with the 5ml Ca/Mg? Something like half a teaspoon?

Keep my Maxibloom around 3.5g or bump it up a little?

LeastExpectedGrower said:

Thank you, as always. Add an additional bit of Epsom to my feed along with the 5ml Ca/Mg? Something like half a teaspoon?

Keep my Maxibloom around 3.5g or bump it up a little?

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Don’t know really. You need to figure out why since you have been providing it. Perhaps something is locking it out.

I believe looking at the wheel I’d drop the Maxibloom for a couple of times.

hotrodharley said:

I believe looking at the wheel I’d drop the Maxibloom for a couple of times.

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Yeah, I was thinking that with the constant drip the Maxibloom at 3.5 would equal a standard 7g feed to waste hand water, but I think what I'll start by adding a gallon or two of water/epsom + Ca/Mg to the tank which would reduce the current feed in the tank until I empty/clean/reset the reservoir on Thursday, then I'll drop the Maxi way down for a week to see if that resets things.

we dont need calmag in soil.

we do need epsom salts with MB

ensure you're getting about 25% runoff when feeding with ph balanced solution

potassium bicarbonate is a cheap PH up salt, additional potassium never hurts

visajoe1 said:

we dont need calmag in soil.

we do need epsom salts with MB

ensure you're getting about 25% runoff when feeding with ph balanced solution

potassium bicarbonate is a cheap PH up salt, additional potassium never hurts

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I was doing epsom salts earlier in the grow, assuming that was true, but then ended up with a calcium deficiency. I started adding 5ml of Ca/Mg per gallon and the calcium deficiency went away...only to be replaced by this magnesium issue...so, yeah...I did need to add calcium. And that was on top of the ~220ppm hardness already in my water.

Maxibloom has plenty calmag...by adding more you're guaranteed to F something up.

I would concur, 5g/G CalMg in addition to the Maxi, in addition to whatever is in the .44 EC water, is likely far too much Calcium

The Maxi + CalMg combo has more Calcium than Potassium; that's not good, likely even worse factoring in the tap water.

Billy the Mountain said:

I would concur, 5g/G CalMg in addition to the Maxi, in addition to whatever is in the .44 EC water, is likely far too much Calcium

The Maxi + CalMg combo has more Calcium than Potassium; that's not good, likely even worse factoring in the tap water.

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Well, I do buy that there's a magnesium deficiency...but here's the thing, I had a calcium issue about a month ago with my water+MaxiBoom and no additional Ca/Mg. So I did bump up the Ca/Mg, and that took care of the calcium issue but then this. I've wondered before if the calcium in my water was actually bio-available or not, there's mixed messages on that and I've run into calcium issues using it in the past too.

For right now I've reset my reservoir with a lower amount of Maxi (1.5g per gallon), kept the Ca/Mg and added in some epsom salts to see if that moves the needle.

hotrodharley said:

I believe looking at the wheel I’d drop the Maxibloom for a couple of times.

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Thursday night I reset the reservoir and cleaned it with 7g of the mix listed above. Today (about a day and a half later) the plants had run through the whole thing, which I haven't seen them do before. Added back 7g with 1g maxi + 1g Epsom + 2.5ml ca/mg... Once that runs through I'll bump up the maxi again and see where that gets us.

I find the blumats can overwater alot. I'm really tweaking around to get proper moisture levels. When the medium is too wet it can cause issues like this too. This is what I've found in my setup as well. If I see the drippers aren't at work I'll stick my finger into the bottom of the pot through a hole. If it's wet then turn it down. If it's moist but not wet then you're good. If it's dry dial it up a cunt hair.

You're right is is likely a potassium issue caused by overwatering. It usually doesn't show up until mid flower then BAM

Jjgrow420 said:

I find the blumats can overwater alot. I'm really tweaking around to get proper moisture levels. When the medium is too wet it can cause issues like this too.

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Hrrrm. The leaves haven't shows signs of over-water, but I'll keep an eye out. Really, the top layer of soil is pretty dry except for within a few inches of the drip. And certainly it's not extending to the outside perimeter of the bags. Maybe I'll dial back and see what happens.

LeastExpectedGrower said:

Hrrrm. The leaves haven't shows signs of over-water, but I'll keep an eye out. Really, the top layer of soil is pretty dry except for within a few inches of the drip. And certainly it's not extending to the outside perimeter of the bags. Maybe I'll dial back and see what happens.

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Just an idea.... It's something I ran into with my setups so maybe it is similar with yours. Just something to think about/investigate

My leaves never showed signs of overwatering either. I think it's likely because it's getting fresh oxygen rich water in the drop constantly.? Not 100 but that's where my mind goes.