Can I accurately test new soil to see what the runoff PH is?

[Konflict]

Fox Farm Ocean Forest Soil low soil pH

Been doing some research on why one of my plant’s soil pH refuses to come up. I have ran across a couple articles that talk about this problem with FFOF during flower stage. Anyone have this problem? I’m recycling the dirt so it very well could be past it’s prime. Starting to see problem signs in the lady. She is an auto and I’d hate to dig her up to transplant in fresh soil bc of the shock factor. T.I.A