I use organic apple cider vinegar to PH down, you could use lemon juice, or normal vinegar. I use potassium silica to PH up, if I PH my water to far down.
Unless you have a PH meter you could go to far the other way, and lock out your nutrients again, and be in the same position you are in now. Until you know what your putting into the soil, you are just guessing. water will rise in PH as it sits in a bucket. My tap water in Nova Scotia is 7.4 out of the tap like yours, when I leave it to gas off the chlorine, it is around a PH of 8.
So putting water in your pot a PH of 6 allows it to rise up to 7 or above also with the help of lime and calcium in the soil . As it rises the plant can access the nutrients at the time it hits the right PH. If you go to low in your PH it will take a lot longer for it to rise up to the right level if it does at all. That will depend on how much Lime/calcium is in your soil to raise it up.
I hope that helps.