Deficiency Help Needed

[Mack420]

Hello everyone, I'm a long time fan of this website and never made an account till recently. I have found this website to be more helpful then any other marijuana message board out there, and the people who contribute to be life savers even hero's. This is far from my first grow but I'm running into some problems week 2 into flower. On some of my tops (and only the tops) there appears to be a slight yellowing and I can't put my finger on whats exactly going on. I cant find any pictures of whats going on so I thought I would ask and see what you guys and gals think. This is my first grow using the Gavita 750 flex de fixtures and I have noticed that my plants vegging under T5's tend to be darker green and do not show this characteristic, but plants vegged under 750s have a slight yellowing. I am currently running a sea of green in flower in 1 gallon pots with BM6 (peat moss as my medium). Plants on the outskirts generally have a more green vigor to them compared to plants directly under the 750s. But from what my research is telling me its either a sulfur, iron, or even a magnesium deficiency. Any help with this problem will be much appreciated. If any more info is needed please let me know

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[Theassbandit]

So my tops did this same thing... I asked some questions on here an a couple people said phosphorus.
Could your light be too close?

 

[Theassbandit]

Are you adding a cal-mag or a mag-sulf. ?

 

[ArcticOrange]

I have a feeling the answer is in the OP.

Hello everyone,...Plants on the outskirts generally have a more green vigor to them compared to plants directly under the 750s. But from what my research is telling me its either a sulfur, iron, or even a magnesium deficiency. Any help with this problem will be much appreciated. If any more info is needed please let me know

 

[germinator]

First of all Welcome..good folks and info here fosho.
My .02.....What's your distance from the canopy on those gravitas? Cuz those babies are bombers.
I been eyeing those but I hear ya need high ceilings and appr. 3ft from canopy.
Those are some pretty sati girls. I go less is more on the nutes. They give me a good challenge too pretty ones always the toughest.
Best vibes

 

[Seamaiden]

That's looking like either a Fe- or S-. Mg- occurs on older/oldest growth usually because it's highly mobile. Immobile elemental deficiencies are diagnosed in large part due to where they occur. This is the very newest growth strongly suggesting (dictating?) that it's an immobile element.

Fe- are much more common IME than S-.

Beyond all THAT, I really think you're going to want to read Capulator's thread on how light spectrum affects nutrient uptake. Things seem to change under lighting like Gavitas based on what I've been reading.

 

[Mack420]

First of all Welcome..good folks and info here fosho.
My .02.....What's your distance from the canopy on those gravitas? Cuz those babies are bombers.
I been eyeing those but I hear ya need high ceilings and appr. 3ft from canopy.
Those are some pretty sati girls. I go less is more on the nutes. They give me a good challenge too pretty ones always the toughest.
Best vibes

The distance between the canopy is about a foot and a half. I have a lux meter that i use and the other day it read about 60,000 lux and two days later(last night) it had reached 80,000 lux. Last night I raised the light to where 60,000 lux is at the top of my canopy so ill check tonight to see if its helped my problem. I know lux readings are not the most accurate but they help me for the time being. Last feeding i gave them 1300 ppm at week two

 

[Mack420]

That's looking like either a Fe- or S-. Mg- occurs on older/oldest growth usually because it's highly mobile. Immobile elemental deficiencies are diagnosed in large part due to where they occur. This is the very newest growth strongly suggesting (dictating?) that it's an immobile element.

Fe- are much more common IME than S-.

Beyond all THAT, I really think you're going to want to read Capulator's thread on how light spectrum affects nutrient uptake. Things seem to change under lighting like Gavitas based on what I've been reading.

Thank you for your input Seamaiden. I always love reading information posted by you. Knowledgeable and reputable. I read through Capulators thread and it makes sense that plants under different lighting take up nutrients differently. This past crop when they were vegging I kept them under the 750 hps and some of my problems that I'm having could be associated with that. Ive been looking into cmh's and my next investment is defiantly going to be them to use for veg. But my question is now what should i do to my flowering girls? I pulled the light up to where my canopy is getting 60,000 lux, canopy level temps are about 72-75 Fahrenheit, and my last feeding was at 1300. I also foliar sprayed last night with aloe vera 200x powder, frass, and true blooms(beneficial bacteria). Im wondering if my problem doesn't clear up that if I should foliar with something containing an iron supplement or change the amount of micros in my feed solution

 

[hawkman]

type of air circulation? fans - look like "heat" burn - move light's up and air circulation will fix this - your new growth will be green - generally nutrient issues start at the bottom leaves - your start's at the top

 

[Seamaiden]

Thank you for your input Seamaiden. I always love reading information posted by you. Knowledgeable and reputable. I read through Capulators thread and it makes sense that plants under different lighting take up nutrients differently. This past crop when they were vegging I kept them under the 750 hps and some of my problems that I'm having could be associated with that. Ive been looking into cmh's and my next investment is defiantly going to be them to use for veg. But my question is now what should i do to my flowering girls? I pulled the light up to where my canopy is getting 60,000 lux, canopy level temps are about 72-75 Fahrenheit, and my last feeding was at 1300. I also foliar sprayed last night with aloe vera 200x powder, frass, and true blooms(beneficial bacteria). Im wondering if my problem doesn't clear up that if I should foliar with something containing an iron supplement or change the amount of micros in my feed solution

I would give them something for that Fe right now because it's immobile. My go-to product is a micronized soft rock phosphate called CaFeMg from Sensational Solutions.