ph in should be 6.3 ph out should be 6.3 You might need to add a little aluminum sulfate to your mix at 4 grams per gallon. Sunshine #4 comes with a ph of 6.9-7.0 out of the bag. The ratio of aluminum sulfate will drop your soils ph to 6.3-6.4 and will be a sweet mix. I would also add 1 dallon perlite to 5 gallons of sinshine for a great medium.
As the medium dries out, the ph goes up through the sweet spots for nutrient uptake. So the day after you water, your ph should be around 6.3 and as the medium dries out, the ph goes up to 6.6-6.7 and down again to 6.3 when you water again.