Yellowing leaves after N supplentation

[sacred-buddha]

Hello!

This is my very first grow and I'm facing issues with the yellowing leaves after the plant started to bloom on autoflower. About 2 weeks after the buds forming, I noticed that the fan leaves started to turn yellow and fall off naturally.

I thought it might be Nitrogen deficiency so I supplemented a little more in order to try to fix the problem, but maybe I used it a little too much and notably my buds stopped putting on weight. The buds continue to grow, but at a much slower pace than they were before this Nitrogen supplementation. The new leaves started to grow dark green, however the bottom leaves continue to yellowing even with the extra Nitrogen.

Maybe she is the her final stage of life at 8 weeks now, but I think the buds are still too small and needed more weight (or even I blew it up by adding more N incorrectly which prevented the buds from forming as they should), and her genetics says 10 weeks MINIMUM from seed to harvest.

Any idea what could be wrong?

More infos:
DWC using GH trio w/ nutes @ 1600ppm
ph adjusted daily to 5,6-5,8
100W LED CXB3590 per plant during veg, then added + 50W for bloom

Here is more information:

Problem: Yellowing leaves at 8 weeks, even after N supplementation
Medium/grow method: hydroponic soilless, 5gal DWC, with O2 Grow Dissolved Oxygen Emitter
Feed and supplements used: GH Trio Gro/Micro/Bloom during veg, then + KoolBloom for bloom @ 1600ppm - EC 3.2 ms/cm (MAX)
water source: tap water @50ppm / chlorinated
Strain/age: Mac-N-Cheese autos / age: 8 week today (from seed)
light used: 100W LED CXB3590 during veg, 150W for bloom; 18/6 hours for light cycle; about 10-12" distance to tops
Climate: temps around 77F, RH 45-65% (hot days can reach 82F in the grow room)
Additional info: ph adjusted daily to 5,6-5,8 (rootzone)

 

[Mañ'O'Green]

Well IMPE 1600 PPM is way to high. You are talking Hanna scale correct? Other things may be going on here. What is the PH in the root zone?

I am going to move this to the infirmary. We can get some input.

Please fill in this form: (copy and paste part is below, this first one tell what specifically to include)

-Problem: (brief description)
-Medium/grow method: soil; soilless-- coco, or peat based like Promix, etc. (please provide the actual product name); DWC, NFT, etc.
-Feed and supplements used: include brand, dosage/strength, frequency of feeding and watering (alone); method-- by hand, drippers, rercirc' or drain-to-waste,... N-P-K #'s too if you can!
-Water source: RO/DI; tap- dechlorinated-?..... EC or TDS reading; pH (don't bother with this on RO/DI, do bother with TDS/EC though to confirm it's working well enough)
-Strain and age
-Climate: night and day ambient T and RH%; res' temperatures; any extremes in T/RH% exposure
- Light used: HID, LED, COB, combo of,... wattage; light cycle hours (20/4, 18/6 , etc.); distance to tops....
-Additional info: PH in the root zone. How long have the plants been affected?...How fast did symptoms appear?... Anything else you think might be relevant..

--Pictures including WHOLE PLANT PICS, and troubled leaves.. use normal light or flash as other light sources ruin color rendering, critical for diagnostics!

✂ - - - - - - - - - - -
(copy and paste)-->

Problem:

Medium/grow method:

Feed: and supplements used:

water source:

Strain/age:

light used:

Climate:

Additional info:

 

[sacred-buddha]

Well IMPE 1600 PPM is way to high. You are talking Hanna scale correct? Other things may be going on here. What is the PH in the root zone?

I am going to move this to the infirmary. We can get some input.

Thank you for moving to the correct forum!

I have added the details in the original post for easy reading. Please, let me know if any further info is needed.

I couldn't take pictures of the root for now, but it does seem to be ok. My biggest concern is the pace of the yellowing leaves that I still haven't found a solution and keep getting worse... and I'm afraid the last N supplementation has reversed flowering to a some extent.

Feeding numbers seems too much, but in conversation with others who grow the same strain, it seems that 1600ppm (EC 3.2) would be the maximum acceptable limit for a good yield on DWC. I have been gradually increasing up the nutes to that limit, without the plant showing clear signs of nute toxicity, but I'm not sure as this is my first grow on autos

 

[sacred-buddha]

Today I went to a complete reservoir change and this time I just added nutes up to 1300ppm / EC 2.6

I am trying to lower the EC in order to improve the nutrients uptake, hope that works...

 

[MMMi]

Is your reservoir EC raising or falling? Res PH raising or falling?

Back when I ran DWC I'd track those to dial in nutes. But I must say, I never, ever went above 1.5ec in DWC.

But this deep into flower, it's hard to recognize improvement. Most of those leaves will never recover even if you fixed the issue.