Help with pH!

Well, I started off growing 2 plants with straight tap water, and they appear (to me) to have pH problems, but I could be wrong. Anyway, my tap water is about 7.3.

I have been watering with water adjusted down to 6.5. And, I flushed and flushed this plant. Then, I let it sit a bit, test the runoff, and it's about 7.2. So, then I made a really acidic solution and watered it with that, and again runoff a bit later is 7.3.

Can anyone please confirm this looks like a pH problem, and secondly, what else can I do to lower the pH? Do I just water with a very strong acid to correct the pH?

Edit: Please see http://forum.grasscity.com/grow-journals/134695-blueberry-grow.html for pictures.

Thanks.