Question: CRS/CBS + New water?

I posted this in shrimp and inverts but thought this might do better over here.

I've had crs/cbs for over a year now, and for the whole time I used a r/o system which i believe had a p.h of 6 for them. Recently parents took out that r/o system and bought a 'better' filter for drinking, and the p.h is 7.5 !! O.O

I procrastinate in water changes, so right now its like 80% full and the 'waterfall' is bugging me, and NOW when I plan on doing something I'm not entirely sure if its ok to use that new 7.5 p.h water? I've always heard that they like the water more acidic and have not had much problem with the 6.0. What do you guys recommend? I thought maybe if i used a little bit of it and mixed it with tap water or ...?

Advice/suggestions please and thank you!