Leaves getting purple, nothing I tried helped

[Generic Name123]

Hello everyone!
As you can see in my pictures, the leaves of my (4 week old Sour Diesel) have gotten purple. She gets 12/12 for a week now but the leaves have been purple before that.
Some other facts :
temp is ~25 degree Celsius (77F) during lightening and ~23-24 degree Celsius (73,5F-75,2F) during "night".
Humidity is >50% at any given time. Mostly even >65%
Im growing in soil and shes gotten new one 2 weeks ago.
I use BioBizz nutrits even though Ive stopped giving some since the edges of the leaves seem burnt....
The PH of the soil is beteween 6,3 and 6,7.

Ive read online, that this might be caused by a Phosphurs defficy, but I am kinda scared to give more nurtrits since the leaves are already burnt...

I really hope you guys can help me!

 

[Pennywise]

Welcome Generic, looks like Nitrogen deficiency. What kind of soil are you using?

 

[Generic Name123]

Thanks for the fast reply !
I thought about Nitrogen defficy too, but if I give her more Nitrogent, wont I even burn her harder?

It's a "hobby growing soil" which I have been using for my "normal" plants for a long time.

It says:
PH: 5,5-7.0
Salt: g/L : <3
Nutrits: 100-500mg/l Nitrogen, 30-100mg/l Phosphate, 400-1200mgl/l Potassium

 

[Pennywise]

Not sure about the soil, if you could add some grow formula it may help. Just keep it on the low side. The burnt leaves could have been light stress too.

 

[Emilya Green]

You have not burned this plant. You are starving this poor yellow thing. Full strength nutes, at the proper pH, ASAP... that is what she needs. You have just moved her into flower where her nutrition needs have changed drastically... now nitrogen is not her primary need, it is potassium and phosphorus... and she needs it now. You will be amazed at how green she will get after you feed her some bloom nutes, but be aware that now that you are playing catch-up, and it is going to take several watering cycles of properly using the instructions on your nutes to fix this.

 

[Generic Name123]

alright guys ! thanks for the help already !