Any probe that looks like this is usually shit.

PH strips are easier and accurate enough for what you need.

I have heard that they are not. I have done pH testing the manual way with strips. They are extremely cheap, simple and accurate.

I purchased one of these thinking it would work.

It doesn't, it's garbage

No. I’ve had a similar one that, even when I stuck it in a glass of water, went no further than “lightly moist” on the indicator. Worthless.