hi there, i have a new area of blueberries that i just transplanted that look like the this: i dug 8" and mixed in a couple of bails of peat moss and 1.7kg of aluminum sulphate. a month later i've take a ph reading with the following device: it maybe barely moves from a ph reading of 7. can a device like this be trusted? irrespective, would it hurt to mix in another 1.7kg of aluminum sulphate? these bushes won't have much of a root system yet so its easy enough to do now. appreciate any guidance!