Is it posible to keep up right PH and EC level ?

Hello everybody, everthing is going right with my ladys, thanx to some of you. first week passed, plants triple thay size, in any posible way, 24h of light dos the work. Im using Terra Vega nutrition line with Terra Profesional soil. My question is, is it posible to keep Right PH and EC level jus by using aksact amounts of nutritiens in the right water. I use top water but i let it sit for a 2 days before i use it. ThanX.

i would say no. too many variables. gotta be vigilant with pH especially.