Nutrient burn or lockout/deficiencies?

Hey everyone,
I have this issue with my leaves turning yellow on the 3rd week of flowering... what can it be?
Thanks for your help

Cookies Gelato #1
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Cookies Gelato #2
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Amherst Sour Diesel
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Mango Sapphire and tent pictures in next post below.

GROWING INDOOR:

• 2x Cookies Gelato (Royal Queen Seeds)
• 1x Amherst Sour Diesel (Humboldt Seeds Organization)
• 1x Mango Sapphire (Humboldt Seeds Organization)

WEATHER CONDITIONS:

• Lights Off
  • 22ºC~23ºC | 72ºF~73ºF
  • RH 55%~60%
• Lights ON
  • 26ºC~27ºC | 78ºF~80ºF
  • RH 50%~55%

TENT SET UP:

• 1,20x1,20m. | 4x4ft.
• Extractor 150mm 650m3/h
• 1x 650w Mega B4 full spectrum LED from Hortibloom (Geyapex)
• 2x 240w Quantum Board 2700K + 4000k LM301H + 385nm UV + 660nm RED + 730nm FR (Bavagreen, separate switches)

Total power used now is 700w: 100w QB left+100w QB right+500w (B4) top

GROWING MEDIUM AND NUTS:

• Canna Terra Professional (CANNA)
• 14 lts pot | 3,7 gal
• Bio Grow (BioBIZZ)
• Bio Bloom (BioBIZZ)
• Top Max (BioBIZZ)
• Bio Heaven (BioBIZZ)
• Acti Vera (BioBIZZ)
• Calmag 2.0 (Bac)
• Trichoderma harzianum (Trikologic)
• Bactohemp (Agrobacterias)
• Silic Boost (B'cuzz)

WATERING SCHEDULE:

Using RO water from the dehumidifier (EC 50 mS/cm). Adding calmag before nutrients as a starting point: 400~450 mS/cm.

Watering every 2 days, 1 liter (0,26gal.) per pot

• 1st week on flower:
  • EC 720 mS/cm / PH 6.3
  • EC 940 mS/cm / PH 6.2
  • EC 1420 mS/cm / PH 5.9
• 2nd week on flower:
  • EC 470 mS/cm / PH 6.3 (calmag only)
  • EC 1600 mS/cm / PH 6.6
  • EC 1640 mS/cm / PH 6.3
• 3nd week on flower:
  • EC 1200 mS/cm / PH 6.4
  • EC 850 mS/cm / PH 6.0
  • EC 150 mS/cm / PH 6.3 (trichoderma only) (today sept. 3rd, 2020)

To continue uploading pics here...

kind of looks normal maybe give it a boost of mag...

Bernie420 said:

kind of looks normal maybe give it a boost of mag...

Click to expand...

Hi @Bernie420

Many thanks for your quick reply! I was in a doubt between making a root flush or stay in a regular nute plan

So in your opinion, what I have here is a magnesium deficiency? Then I may go and get some epsom salt or similar tomorow. Gracias amigo!

cabriolas said:

Hi @Bernie420

Many thanks for your quick reply! I was in a doubt between making a root flush or stay in a regular nute plan

So in your opinion, what I have here is a magnesium deficiency? Then I may go and get some epsom salt or similar tomorow. Gracias amigo!

Click to expand...

If you dont think you have a hot pot then dont do a flush....but i recommend doing a flush half way through flower just to clean things up...add back some microbes if you flush.

A little extra mag isnt going to hurt anything, then a little later in flower a little extra potassium is recommended. Research what mag does .....and K in late flower. or in general. Its what the plant wants the most. Harley smith has some good videos on the y tube about plant nutrients.

Once you get a few grows under your belt and get some learning you can anticipate what deficiencies are going to pop up. And most of the time you dont even want to chase a deficiency in late flower unless it got away from you. Its the normal cycle of the plant to have yellow leaves and such in late flower. I said late flower not week 4 so........

IMO your plants look normal so stay on course and a little extra mag will help keep things rocking and wont hurt a thing. Like water in 250 ppms of mag now and in ten days or so.

@Bernie420 mate!
Thanks a lot for taking your time to read my "too long" post (sorry for that) and help me to fix my crop.
Your knowledge is much appreciated.
Sweet smokes