Flooding every 4 hours seems excessive, I would reduce the frequency to every 6 hours initially and assess the how the plants look at that point with your current EC, Keep in mine even though other grows are at the same week with a higher EC those plants could require different nutrient needs or can even tolerate higher nutrient needs than yours.
Overall your plants look healthy and green, they are a little droopy but that might be resolved if you change the water frequency