Frost: Cold Plunge Care

Pay once. No subscription, no ads, no account. Works offline. Frost is the iOS cold plunge water-chemistry assistant. Enter your sanitizer and pH readings, get exact doses scaled to your plunge's volume. Whether you run chlorine or hydrogen peroxide, Frost gets the math right — and warns you before the two ever meet. Features • Dual-path sanitizer math: chlorine (Dichlor 56%, Cal-hypo 68%, liquid 12.5%) or hydrogen peroxide (3% household, 35% food-grade) • Drain-required safety interlock when switching sanitizers — chlorine and peroxide chemically neutralize each other • Handling advisory for 35% food-grade peroxide (gloves, eye protection) • Tub-type-aware water-change cadence — chillers vs DIY chest-freezer builds get different intervals • Symptom-first cloudy-water diagnostic — "Water looking off?" is the hero card, not a buried sub-screen • After-session top-up doses based on people × sessions • Filter rinse, deep-clean, and replace cadence tracking • Cold-water test-strip context — strips read slowly below 50°F • Locale-aware metric/imperial units (liters or gallons), comma-decimal input supported • Universal app for iPhone and iPad For cold plungers running 80–120 gal / 300–450 L home setups — chiller-based, DIY chest-freezer, or somewhere in between. $3.99 one-time. No subscription, no ads, no account, no cloud. Privacy: Frost collects nothing. No analytics, no accounts, no network requests. Your settings live on your device.