David,

It could very well be my imagination but 7.5 seams to feel a lot different than 7.2 on the eyes.
I don't think that's your imagination. It's been posted on the forum before that higher pH is closer to the pH in your eyes and that it WILL be more comfortable....seems like human pH (at least for the fluid in your eye) was up around 8.0 or perhaps a little higher. The trade-off is the loss of effectiveness of the Cl at that pH.

Didn't mean to hijack the thread but I think DavidD's observation is interesting.