Help! Is this phophorus deficiency or nute burn?

[curryguy]

• Tent: Gorilla Shorty 4’x4’
• Lights: Mars Hydro TSL 2000 (2x300w)
• Exhaust ventilation: UFO THERMO (400 m3/h / 235 cfm)
• Fresh air: VENTS QUIETLINE (200 m3/h / 117 cfm)
• Carbon Filter: PRIMA KLIMA (480 m3 / 282 cfm)
• Air movement: 2x 15cm/6" Fans
• Hydrosystem: Atami Wilma 8 drip irrigation with hydroton

2/8 plant have this problem. Temperature has been bit high (80f). I use GHE flora with Lucas formula + calmag + bloombooster. Its 5th week of flowering.

PH has been mostly between 5.7 - 6,2.
The EC started to rise quite fast 1.5 -> 1.79 (in one night). So I did change the res, flush yesterday.
After that the EC dropped from 1.29 -> 1.19 during last night.

Please help I am affraid I lose the plants

Please

 

[JASONBROTHER]

From the symptoms of your leaves, it's a little bit like calcium deficiency，cuz there have brown spots on leaves, But paradoxically, plants usually don't need much calmag after the 4th week of bloom.

I found that the leaves and tips nearest to the light, has burning symptoms, Normally, in the last few weeks of flowering, about 690 PPFD is usually required.

and ur EC started to rise quite fast in those weeks, and I have learned that some commercial growers in hydro tend to decreased slowly and kept about 5.5 at the beginning stage of Veg in the last few weeks of flowering。

 

[curryguy]

From the symptoms of your leaves, it's a little bit like calcium deficiency，cuz there have brown spots on leaves, But paradoxically, plants usually don't need much calmag after the 4th week of bloom.

I found that the leaves and tips nearest to the light, has burning symptoms, Normally, in the last few weeks of flowering, about 690 PPFD is usually required.

and ur EC started to rise quite fast in those weeks, and I have learned that some commercial growers in hydro tend to decreased slowly and kept about 5.5 at the beginning stage of Veg in the last few weeks of flowering。

Thank you for your contribution!!!

I raised my light also yesterday (to 18") the light intensity is around 972 uMol, do you think that is too much?

 

[JASONBROTHER]

Thank you for your contribution!!!

I raised my light also yesterday (to 18") the light intensity is around 972 uMol, do you think that is too much?

Science can answer your questions
Lol

 

[JASONBROTHER]

Thank you for your contribution!!!

I raised my light also yesterday (to 18") the light intensity is around 972 uMol, do you think that is too much?

The best way is to do your own calculation and get your PPFD through DLI calculator，
And then watch her reaction, she will tell you everything it needs,
Cuz everyone's garden is unique, no one can give u specific answers .but science can

 

[curryguy]

Science can answer your questions
Lol

Oh shit, wonderlful!! Haven't found one like this before. TY!!!

 

[JASONBROTHER]

I u have more questions u can @Aqua Man
He is my teacher

Oh shit, wonderlful!! Haven't found one like this before. TY!!!

If you have more questions, I suggest you consult with
Aqua man in this forum , I am his apprentice. He is very kind and patient.
What's important is that he can let you understand why you should do this, not what you should do