It was a bad week...with a happy end!
I forgot to turn on the exhaust after i installed the bigger light + the weather was hot...the rez got to 33.5°C...probably over 20h...
Roots went from white to brown within 24h..i thought everything is lost..plants looked aweful on top and bottom..
Just before all that i added first beneficials(TNC mycorrmax hydro)...they must have saved me...because just today i checked again and now i see loads of white roots coming out of the brown slimy coating...plants also don't look worse and keep growing healthy new tips
As it looks mycorrmax won the battle!