Red stems / phosphorous deficiency? Athena Pro line, Rockwool

[flipflop64]

I just transplanted into slabs. I think i had them in 4inch block for too long and fucked them up. First time using the small grodans.
When do you usually plant into slabs? Thanks to everybody who takes the time to answer, i really do appreciate it.

 

[Oldguy71]

They’re looking better to me. The red stems won’t fade for a long time.

 

[BonanzaGmx]

Was you able to solve it? Currently into the same issue, with the purple stems. Tuning athena pro line 3.0ec input and 6.0ec out have spoken to athena guys and told me it’s good ec media value.