I preface this with i am a newb. I was told by my hydro guy that COCo being hydro should have a PH of 5.5-6, and a soiless mix such as soil-coco-perlite should be about 6-6.2.
I must admit i dont understand why a soiless mix that contains soil is called a soiless mix. wow thats a tongue twister!!
Good luck, hopefully an expert can chime in.