Yeah, I'm basically stuck with that, too. My only concern is mixing the lower PH distilled water in during my water changes and the fluctuation PH. I was hoping with the KH being lower, that would have kept the PH at the same, lower level...
Same on this end - very odd (I'm mixing in soft, hard, and distilled water - everything is getting into the right softness/hardness except the stubborn PH)
I have a similar issue and was wondering if there is a point where my KH will be low enough to start keeping a lower PH? My tap is really hard water (30 GH, 15 KH) with a PH of about 8.2. I’m mixing in some distilled water and I’m at 5 GH and about 5-6 KH, but my PH is still 8.2. The water I’m mixing in is a lower PH but my tank PH isn’t budging. I need to continue mixing water for a softer water, but I’m just really curious on why the PH won’t budge. Something else must be buffering that I’m not seeing.