with a 6.6 ph and a 7 from tap I don't think there would be enough of a flux at water change time to worry about it. I advise against lowering or raising your PH unless it is a huge difference which .6 is not. I think she is acting normal other than it does look like she is trying to get ahold of something to eat it, I agree maybe she sees something in the reflection or something that she thinks might be edible. Every ray is different.
