PH of tank vs tap water

[Steves55]

My tank has a PH of 8.4 while my tap I thought had a 7.4. This alarmed me- why the spike? After talking to a friend, I filled a vial with tap water & retested 12 hours later. Now it's 8.4, same as my tank. So now what?

Tap water on left, same tap water 12 hours later on right. Should I treat tap water with PH down prior to putting in tank for top off/changes?

 

[Caliban07]

Likely carbonic acid (co2 in water) is responsible for the lower pH in tap. After a while it leaves the water and pH rises.

It’s no big deal though. Plant’s and fish will be fine.

 

[Steves55]

This is the first tank I set up since moving here. My other tanks are in storage. Last house had well water & all tanks were at 7.6 inc the well water. Was just alarmed at how high the PH of the tap water here was.