PH Confusion. Please help

[andrewsk]

Hi guys. I am hoping you can give me some advise on what to do.

I am new to the hobby and have been playing and testing PH levels. I have 2 test kits and a PH Pen.

When I first make RO/DI water and test the PH it bottoms out on the PH test chart meaning it is below 7.4. PH pen shoes just below 7.

Next I add Instant Ocean Salt and retest the PH. 8.2 on all tests. Great.

Next I add a buffer (Seachem 8.3) according to the directions (1 teaspoon per 20 gallons). When I test the PH it is off the charts and PH pen shows 9.8??

Then I tried, RO/DI water, Instant Ocean and some Kalk with no buffer. 9.8 again.

What am I missing here? Should I be adding way smaller amounts than the directions?

Right now, I am sticking with plain old Instant Ocean and RO/DI until I can figure this out.

My tank is at 7.9 to 8.2 depending what test kit I am using.

Any help is greatly appreciated as I am lost!