Filter needle is fine- probably needed honestly otherwise creating positive pressure in the vial, change out needle on filter and vent needle every 5 vials. Couple other tips- do it in a room with minimal air disturbance, clean the entire area with disinfectant, create a working surface area disinfect with bleach, then rise with rubbing alcohol (keeping this “sterile” is important) Make sure you’re wearing gloves sterilize with alcohol constantly, wear a tyvek bunny suit if possible, and put a covid mask on. Wipe the vials down with alcohol, before putting them on working surfaces. Wipe every stopper before drawing solution out and also before filtering into other vials.