[COCO][Zkittlez Auto]Brown patches and yellowing leaves

[grematore]

Hi, third grow here, first in coco.

I've ever had issues with feeding, with soil I always had toxicity problems, this time they seem more deficencies problems.

-Problem: in 1 plant upper leaves have tips pointing down , in te 2 plant some leaves have a lot of small brown or gray pathces.
-Medium/grow method: Canna COCO Professional + 20% Plagron perlite
-Feed and supplements used: Advanced Nutrients Sensi Coco Grow/Bloom A+B, Voodoo Juice AN,B-52 AN,Sensi Xtra CALMAG AN,Big Bud AN. I feed every day with 2.5lt each Ph 5.8/5.7 and 1.4 EC right now (always half a dose from the recommended schedule)
-Water source: RO Water bought from the store (my tap water sucks 1.2 EC)
-Strain and age: Zkittlex Auto from FastBuds, they've planted on 12th September so they're like 48 days old
-Climate: night and day ambient T and RH%; res' temperatures; any extremes in T/RH% exposure T is always beetween 23-27°C - Rh was a little high (65%) so 3 days ago i've started using a dehumidifier to keep RH at 55%, this has raised up temperatures a bit
- Light used: LED Migro Aray 240W kept at 24/0 until today. Right now I started using a 20/4 schedule, this is mi 3rd grow and i always used 24/0.
-Additional info: this color on leaves started appearing a week ago in just medium section leaves, 2 days ago some leaves also started fading out;The plants ar really bushy in the mid zone.

Additional Pics:

 

[Mañ'O'Green]

Yes that looks like calcium lock-out probably too much calcium. The plants look over-fed some. Are you fertigating to run- off. If not you probably need to flush. What does the AN schedule say? I don't see them recommending more calcium with the coco base nutrients? They may already have plenty since it is designed for coco?

 

[grematore]

Yes that looks like calcium lock-out probably too much calcium. The plants look over-fed some. Are you fertigating to run- off. If not you probably need to flush. What does the AN schedule say? I don't see them recommending more calcium with the coco base nutrients? They may already have plenty since it is designed for coco?

I saw many people online using calmag + sensi coco so i did the same.
I’ll stop using it from now on.
What should I use ti flush with coco?
I know that coco should never be watered with plain water.

thanks
Grematore

 

[Mañ'O'Green]

I saw many people online using calmag + sensi coco so i did the same.
I’ll stop using it from now on.
What should I use ti flush with coco?
I know that coco should never be watered with plain water.

thanks
Grematore

I know peeps flush with just PH water but I agree with the idea that that is stressful on the plant. I would do a 30% strength balanced nutrient flush to 30% run-off each time over the next 3 fertigations. So that at the end of three sessions you will have replace 90% of what was in the pot to 30% strength. Then go back to your normal feed schedule.