See exactly how pH affects every nutrient your plant needs. Wrong pH is the #1 cause of deficiencies — even when nutrients are present in your medium.
~70% of all nutrient "deficiencies" are actually pH problems. Your plant can be sitting in a perfectly mixed nutrient solution, but if the pH is wrong, the roots physically cannot absorb certain elements. This is called nutrient lockout.
Different mediums have different sweet spots because of how they buffer pH. Soil has natural buffers (organic matter, lime) that keep pH more stable. Coco and hydro have almost no buffering — pH can swing fast and needs constant monitoring.
Pro tip: vary your pH slightly within the target range between waterings (e.g., alternate between 6.2 and 6.5 in soil). This ensures every nutrient gets its turn at peak availability.
Measuring pH before mixing nutrients — always pH AFTER adding all nutrients. They change the pH of your solution significantly.
Ignoring runoff pH — input pH matters, but if your runoff is wildly different, your root zone pH has drifted. Flush and reset.
Using cheap pH pens — calibrate monthly with buffer solution. A miscalibrated pen is worse than no pen because you'll make confident wrong adjustments.