i am currently starting a grow box using 2 bins one upside down on top of the other. My last grow was using MG and now i am going to start using MG organic mix because of the nute problem. Should i mix it with pearlite before i begin to plant my seedlings or should i wait and put pearlite when i see a PH difference???

Thanks in advance for any help and i will be sure to post my grow as soon as i start...