Lets see,
Here's some good info on ph.....
If your runoff pH is higher than your starting pH, use this equation to determine your soil pH:*
Soil pH = Runoff pH + Difference
If your runoff pH is lower than your starting pH, us this equation:
Soil pH = Runoff pH - Difference.
For example, say your the starting pH of your solution before it goes in is 6.5 and the pH of your runoff is 7.0. The difference is +0.5, so using the above equation:
Soil pH = 7.0 + 0.5*
Soil pH = 7.5
If your starting pH is 6.5 and your runoff is 6.0, your difference is -0.5 and using the above equation:
Soil pH = 6.0 - 0.5
Soil pH = 5.5
7.6 - 2.5 = 5.1
I would ph every thing to 7 for a week or 2, that should get you up to 6.5
or you could flush with 7.5 2 times pot size then water with a nutrient solution at 6.5 and re test your run off?