should never have to flush in coco.. means you are feeding too much, if you do.
soilless -- 10% runoff waste water from each fertigation. Always fertigate. 1.2-1.5EC concentration at roughly 6 pH. good quality soilless nutes should be ph-balanced on their own. Avoid this hassle and buy a product that ph-balances on its own, lol.
n 120-13
p 60
k 180-200
Ca 100+
Mg 50-75
S 100+
good ballpark ppms for each... this avoids any differences between US label standards and those of your region. phone apps and online ppm calculatores can take the guaranteed analysis label information and spit out PPMs.