HidrateSpark PRO can blink after you take a drink from it, showing that it has processed the drink you just took. The Sip Glows switch is on the Profile -> Reminders -> Bottle Glow Reminders screen and is marked "Glow when I take a drink (HidrateSpark PRO only)".
Please note, when turning Sip Glows on/off, the bottle has to be connected to your phone.