Super high pH, don't know why

[Delphinus]

I'm running my 65g FW on tapwater (whichtests out at pH=7.5 and KH=11).

Substrate is a mixture of Flourite, Eco-Complete, and some kind of lava based substrate which is supposed to be good for plants. There's also several pieces of Malaysian driftwood.

I was about to look into getting CO2 running again, and thought I would take some tests to establish a baseline before adding any.

The pH probe shows pH=9.0.

Not believing that, I went out and bought a dripwise pH test kit and it tests out at 8.4.

What would be pulling the pH up so much?

I could filter some peat moss to bring down the pH, but I wonder if there's something I should be taking out of the tank as well.