All you need to remember is that all soil grows need a ph of 6.5-6.8 and hydro is 5.5-5.8 but when in veg stage also in hydro ph can go to 6.0-6.1
With a soilless mix i should imagine that ph would be somewhere in the 5.0-5.8 but now im only gessing. Hope this helps you out abit scunk