SOIL Plants are drooping with some leaves going brown

[Stevepmd]

Hello,
Im growing 5 plants in ProMix HP. Im also using General Hydroponics Flora series.
I keep the PH around 5.8 to 6.2.
I have been following the feed chart. So I did a plain water flush with a 6.0 ph.
I tested the run off water and found the PPM over 3000 PPM!!! .
So now the run off PPM is 220 my tap water is 175 PPM.
What am I doing wrong.
See photos.

[Toker1]

Droopy leaves are typically signs of bad watering practices. PH seems a bit low for soil. What PH value does the soil manufacturer recommend?