What is the right PH and EC level?

Depends mostly on your ferts / medium. don't blindly follow any suggestions. e.g. some say coco should be 5.5-6.0, but my fertilizer made by people with doctorate would argue otherwise, lol. So, even with a good guideline, you still need a little trial and error per seed... sometimes a slight pH change can fix everything. Ratios, concentrations, pH... all impact how they will be used, how they compete with each other etc etc... it's incredibly complicated, so you get lots of anecdotal options that only work in esoteric contexts. EC will tell you if nutes are building up in the soil. you get too far over 2100, think about diluting it back down. So, hydro typically recommends a lower pH due to incredibly available and chelated nutrients. In soil you typically have a higher pH because you want to aid matabolising nutrients that are not as readily available. soil - 6.5-6.8 coco - 6.0-6.5 water reservoir or ebb and flow of liquid etc - 5.5-6.0. Again, if your nutrients say something specific on the label, start there over any of this mumbo jumbo.