Purple discoloration on fanleafs

High Guys
Doing a Hepmy Bucket SOG which went amazing so far but since a 2 days some upper fan leafs start to turn purple and I don't know why
Deficency or overfertilisation?
I really don't know what's going on
Here are the Infos
BT 45 of a 65 days strain
Hydro with NPK 5-16-17 EC 1.7 drain 2.0 starting from RO water with Calmg and Si.
ph 5.8 drain 6.0
Roots look fine I think
Watered every hour ATM with 10-20% Drain

Temp 26C and humidity 55% controlled with dehumidifier.
I give them around 800umols of light

Hope someone can tell me what's going on
Thanks and stay high!

Might be genetic. Seems normal to me.

Are you sure?
I know the discoloration starting from the sugar leafs but between the leafveins on Fanleafs?

Should be genetics. Purple would say mg deficency but your leafs are all healthy

Looks genetics to me your looking pretty dialed in to me