Yup that would do it.. it's getting reading from the water.. But I don't know how accurate those things are... Don't even care bother about ph in soil really unless you see problems or you want to learn about your soil, your standard over the counter potting mix should be fine. Getting good mixture of like Worm castings, perlite and a lighter organic soil is even better. Hydro grower so I know how important PH can be..