Are they Ph perfect?
Sadly, no lines currently available on the market are actually pH perfect. Our line is pH stable meaning that after it's mixed into a solution, the pH won't fluctuate, even after 2 weeks of sitting stagnant.
As for self buffering, it's simply impossible. If a nutrient solution has a stable pH and water pH is variable (based on where the water comes from), then the water quality will always have an effect on your post mixing pH. You may land right on that sweet spot, but more than likely, you're going to have to buffer.
Joel