I missed the bit somewhere where he over filled.The statement to ignore that air gap is certainly the recommended procedure to use any syringe, but it might confuse the OP here since he is presumably forced to measure from the air/water interface both at the start and finish of the titration (which is OK) since he overfilled the syringe past the 0 mL line and pulled the air/water line up to the 0 mL line.
For the OP, here's how to properly read a syringe:
https://www.reef2reef.com/threads/reef-chemistry-question-of-the-day-161-using-a-syringe.226267/
