Your koi pond deserves a real logbook — private, offline, yours forever.
KoiLog keeps your whole pond in one fast, beautiful app that never asks for an account and never sends your data anywhere. No cloud. No tracking. If it's in KoiLog, it's on your phone — period.
WATER TESTS YOU CAN ACTUALLY READ
Log temperature, pH, ammonia, nitrite, nitrate, KH, GH, salt, dissolved oxygen and TDS in seconds. Every parameter gets its own chart with the koi-safe range shaded in, so a creeping ammonia problem is obvious before your fish feel it. Touch any chart to inspect a reading. Colored status dots and a "needs attention" summary on the pond card tell you instantly what's fine and what isn't.
POND CALCULATORS — FREE FOR EVERYONE
• Pond volume from dimensions (rectangular, circular, oval or irregular, feet or meters) — and save it straight to your pond.
• Pump turnover: is your pump moving enough water for koi?
• Treatment dosing: type the rate from the product label ("5 mL per 10 gal") and get the exact dose for your pond, split into as many doses as you like.
• Salt calculator with per-dose guidance.
FEED BY TEMPERATURE, NOT GUESSWORK
KoiLog reads your latest water temperature and tells you what to feed and how often — wheat-germ in cool water, growth food in summer, and a clear "do not feed" through winter dormancy.
EVERY KOI, EVERY INCH
Build your collection with 20+ varieties from Kohaku to Kumonryu. Track length and weight with growth charts, keep a photo timeline of each fish, and record purchase price and estimated value.
NEVER MISS MAINTENANCE
Water changes, filter cleans, UV bulbs, skimmer baskets — set the interval once and KoiLog reminds you, shows what's overdue, and keeps the full completion history.
ALSO
• Treatment log with active day counter
• Pond journal with photos
• °F/°C, gallons/liters, local currency
• Dark mode, haptics, VoiceOver support
• Start with a fully editable example pond in under a minute
KOILOG PRO (optional)
Free covers one pond, five koi, three tasks and 30 days of water history. KoiLog Pro unlocks unlimited ponds, koi and tasks, full water history, collection stats (value over time, growth leaderboard) and CSV export.
• Lifetime: $29.99 one-time purchase — not a subscription, never renews.
• Monthly: $2.99 per month, cancel anytime.
Payment is charged to your Apple ID account at confirmation of purchase. The monthly subscription renews automatically unless cancelled at least 24 hours before the end of the current period; manage or cancel it in your App Store account settings. Prices may vary by region.
Terms of Use (EULA): https://www.apple.com/legal/internet-services/itunes/dev/stdeula/
Privacy Policy: https://tobyberg43.github.io/koilog-site/privacy.html
Made for koi keepers who'd rather be at the pond than fighting an app.
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