I have a cal/mag deficiency in week 4 of flowering...

Hey growmie 👋,yeah, looks like you are right it's. early cal/mag deficiency showing up on the older leaves—bit of interveinal yellowing and some rust spotting too. ✅ For cal/mag, the standard range is around 1–1.5 ml per liter of water. ✅ Since you’re already in flower (week 4), I’d recommend 1.5 ml/L to help cover the plant’s increased demand. ✅ Make sure your pH is in range (5.8–6.2 for coco, 6.2–6.5 for soil) so the plant can actually absorb it. ✅ You can feed cal/mag every watering or at least every second one until symptoms stop progressing. Also double-check your overall EC/PPM—sometimes lockout from salt buildup can mimic deficiencies too. If runoff EC is too high, a light flush with correct pH and nutrients after can help. Good luck 🤞🍀♥️