Massive bruh moment over here, it is explicitly told that you should measure ph after adding the nutrient solution. Plagron: "Always prepare your nutrient water before you determine the pH level with a pH meter".
Well, I feel dumb. anyhow mistakes made and lessons learned. THANKS EVERYONE FOR FEEDBACK. I cannot select somethings as an answer for some reason but special thanks to: modmyplants, m0use and scrubbyjimbob.
I now understand why the ph of my solution / run-off is so much lower than what I measure, my goal is usually 6 - 6.1 but after nutrients it does down.
like