Pink stems and leaves starting to fade a bit

[Dfirstever]

Is tbis natural i have2 300 w mars hydro led not the cheap ones niether tens tems is 73 to 76 45 to 50 humidity i just few plant a 3bpart base use all year front to start its not many leaves few of older fan leaves going yellu between v iens

 

[Hydroholic]

What are you spraying them with?