Bro, your pH 7 is not normal for hydroponics! For that age, make it pH 5.5-5.6! Closer to the end of the vegetative stage and the beginning of flowering, make it pH 5.6-5.7! During flowering, pH 5.7-5.8! At the end of flowering, pH 5.7-5.6! During flushing in the last week, pH 5.6-5.5!
A complete diagnosis on pH and your problem! So this issue doesn't come up! 👌
With an EC ratio of 0.5 ppm, even 450 at that age won't create this "hell" that's happening with it at pH 7.0! High pH is always HELL! 👆
Good luck, bro! ✊😇