You can find instructions here. Distilled water works fine and is probably better than RO from what I hear. Scroll down a bit for the test that says Slurry Test.
Testing Ph In Your Soil - Aptus Holland
In this article we’ll show you how to take pH measurements in your soil. I can hear you think, why would you need to measure the pH in your soil when you already measure it in the water you give your plants? Well, your soil is alive, and there are all kinds of processes going […]
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