Water PH

So a few weeks back I tested my tap water from the hose to be at approximately 7.5.

I read that Datnoids prefer 6.5 to 7.5. So I did some reading and from what I could gather adding driftwood would lower the PH a little. So I added 3 pieces of drift wood and now my tank water is yellow from the tannin.

I test again giving the driftwood time to do their magic and now I have a PH reading of 8.0. How the hell does that happen?

I really don't want to buy chemicals to adjust the PH lower, my datnoids look fine and eat like pigs.

So think its okay to leave the PH at 8 or should I go out and throw money at the problem?

Yeah I gotta stop freaking out over the littlest things.

My water is crystal clear, as clear as brown water can be. The IT's are eating everything before it even hits the floor and the Severums seem to mind their own business.

I think I'll leave well enough alone.

Bare bottom tank with 3 large pieces of driftwood. I did yank out this cement looking cave that I had in the water and did a water change. I think I forgot to mention that I had that in there to begin with, even before the driftwood.

I tested the water immediately after, but it was somewhere in between 7.5 and 8.0. I probably will do a water check after every water change to see that it's not changing too drastically. I think the cave was the culprit of the change though, because water straight out of the tap is 7.5.