Besides guessing, you do need a PH meter. They’re about $15 but you also need to measure EC which is relevant to your feeding schedule with any plant. Low Ph indicated (usually) heavy ACID content or excess nutes . To Raise PH to an acceptable target level ( 5.5-6.0) in hydro and 6.0-6.5( 7.0) in soil as soil usually holds more nutes and hydro is relatively more easier to maintain bc you can make adjustments faster simply by exchanging and doing a complete flush. Soil doesn’t allow that option, bc of the mud suffocation factor for roots with excess water on soil. Also get. PH chart that tells you what elements of the Nute is taken up at certain PH levels. Knowing this tell u how to correct specific deficiencies and how to identify the SPECIFIC cause of your problem. Someone mentioned “yellow leaves”. Where it’s a sign of disease but triggered by ex: over watering… but that’s likely HIGH PH (or alkaline water, and a lock out of Nutes that would be taken up in the lower range…iron, copper, and Zinc. So it’s not as simple as just “PH.” Monitoring PH has a specific call and action so to speak. Hope this helps whoever is reading. It’s not a contest… it’s a class.