Measured EC and burned leaves

ratios are just as important to dial in as concentration... in this case you must have something too high or too low... never assume tox or def until you assess the symptoms. They can easily overlap in many situations. Looks like either a k-deficiency or a N-deficiency... Paling from bottom up and tip in on leaf is how N-def progresses. k-def affect older leaves first, too. It will show interveinal chlorosis before necrotic spots also develop. most distinguishing sign is the leaf tips -- which burn. All the crispy leaves, i'd lean toward K - deficiency. consider what you feed and any recent changes over last couple weeks. Check pH to make sure that's not an issue... Soil has so many unkowns.. how you saw this progress will help you diagnose cause.