1.00 EC could be; 700ppm @.7 conversion (truncheon), 640ppm @ .64 conversion (eutech) 500ppm @ .5 conversion (hanna most hanna at least) and i even heard of someone or some company using a 1.00 EC= 940ppm @ .94 conversion.
That chat only refers to one of NINE different conversion rates. Make sure yours matches or the numbers are all bogus.
Further, the chart has never met: you, your plants, your water, your system. It knows nothing about what you're doing or the tools you're using. Your plants on the other hand, know exactly what's going on and are incapable of lying to you. Don't ask a chart, ask your plants.
EC up, pH down-too rich
EC down, pH up-too lean
EC flat, pH flat-balance.
HOWEVER, flat readings do not mean all nutes are equally absorbed and can lead to imbalance over time. Because no one pH reading allows absorption of all nutes, a small swing is better for you.