1st Time Grower

Just know it's more art than science. All sorts of things can cause odd readings that are not representative of reality. Whether you do soil slurries or test runoff etc... be consistent about how you do it. Don't react to the information, initially. Learn what 'normal' is for you methods of measurement -- also assumes healthy plants long-term... Then you can react to things that deviate from that norm and maybe avoid a problem before it starts... but i wouldn't trust the exact value it spits out. Level of moisture will greatly impact it (probably best after a watering rather than as it is nearing the next watering). If testing runoff whether you do it early or late in the runoff will impact it. If you make a slurry, the pH of the water you add and how much volume you add will greatly impact it.... Greater familiarity is needed than just measuring it in order to use that infor in an effective way. Heck, the probe physically bumping into something could cause a whack-a-doo reading.. some dissolving bit of nutrition in proximity to the probe, a chunk of dried up solute if testing runoff etc etc.. pH balance anything before you add it, and stick to normal watering practices and you'll be fine. The microbes in your soil are going to mitigate and at least partially dictate resting pH.