what are some household soils like miracle grow etc. that have the correct ph for weed or are they all fine?
I don't think the pre-existing pH of your soil really matters...just make sure to check your runoff pH and the soil pH after watering. And make sure you choose a soil that doesn't have slow-release fertilizer (if any at all) to make sure you don't nute burn your plants.
Stay away from anything that says acidic soil, there are plants that love an acidic pH so there are some products just for that, but not right for MJ. Also stay away from anything with time-released ferts added to the soil. Otherwise roosta is right, your pH is the result of your water, nutes, soil, amendments, etc all interacting.