I agree, this is my first grow in coco loco and auto's and have been measuring the pH and ppm run off and
Flush with ro water, or if your well water is a low ppm use it. You can also buy distilled water. But put enough water thru to have it run out. I feed when my plants water run off ppm is lower. I'm still learning coco loco so this is a trial and error thing. My last run off was 400 and i fed them 650 ppm and that took them to high 800 run off. To fix all I do is not feed them for x number of waterings and when the ppm goes low I feed. Not sure if that is correct but it's working for me.
And my nutes are.
Gn flora series,
cal-mag, silica,
hydroguard.
For flowering I'm using Lucas formula.
1 part silica wait 20 mins
1 part cal mag
1 part micro
0 part grow
1 part flower
1 part
hydroguard
Good luck and remember document your grow.