i had a pH problem in my soil grow too. i'm using miracle grow (i know..) african violet soil. i had added lime when i made my soil mix, but like you, i had a faulty pH meter. it was some crappy digital pH meter that turned out to be not very accurate at all. about halfway through my grow i had switched to a different brand of RO water. using the digital pH tester it showed ~7, but using my drop kit, for some reason it pH'ed ~5. (the first water i was using pH'ed at 7 with both the digital and the drops). i was watering with that for a while, and thought my runoff pH was okay the whole time (using the busted ass digital pH meter) but using the drops, it was down to ~5. not good. i first thought something was wrong when i noticed some yellowing of leaves in weeks 2-3 of actual flower. i'm pretty sure it's a nitrogen lockout because of the soil being too acidic..
i tried using pH up in the water like you did, but i couldn't get the run off to come up at all. i had done a couple feedings with mg cactus food (2-7-7) and african violet food (7-7-7) earlier in flowering (haven't since, only water now) which helped bring up the pH of the water i was giving her, but still no change in the runoff. so then i added some lime below the surface of the soil and did a heavy watering about 1.5 weeks or so ago, and last night when i watered i noticed the runoff pH looks like it's come up a bit. the problem with soil is that anything to really change the soil pH takes some time to work. right now i'm in week 6 of actual flowering, and i've kind of given up on trying to fix it. from what i understand they really don't need much nitrogen now anyways, the buds look good and are still growing, so i'm just going to continue my watering and hope the lime can help fix it a little bit, but i think the damage has been done. this is my first grow, so whatever i end up with, i'll be happy, and i know for next time to add more lime to the soil starting off.
for your plant(s) i think you'll be okay. just keep an eye on them and the runoff. from what i understand, the soil buffers the pH of the water, and just using more basic pH water really doesn't do much. i'd let your girls dry out pretty well and then if you can, get some dolomitic lime. use the dosage recommendations on the bag, and then add it to the surface soil (kind of mix it in if you can) and then just water. the good thing with the dolomitic lime is you don't really need to worry about cal/mag deficiencies at the same time you're raising/buffering the pH of the soil.
you can look at my grow thread (see sig) and see what my plant looks like with the low pH soil and N def..and the progress of it..
