TankDiary: Aquarium Tracker

New: the nitrogen cycle tracker. Log ammonia, nitrite and nitrate and TankDiary tells you what stage your new tank is in — and when it's safe to add fish.

The aquarium logbook that respects your wallet: pay once, own it forever. No subscription, no account, no ads — your tank data stays on your phone.

New tank? TankDiary reads your ammonia, nitrite, and nitrate tests and tells you exactly which stage of the nitrogen cycle you're in — and when it's finally safe to add fish.

KNOW WHEN YOUR TANK IS READY Cycling a new tank is where most beginners lose fish. Log your ammonia, nitrite, and nitrate as you go and TankDiary plots the classic cycle curve, names the stage you're in, and tells you the one thing to do next. It won't call your tank cycled until it has actually watched it process waste — no false all-clear.

TRACK WHAT MATTERS Log temperature, pH, ammonia, nitrite, nitrate, GH, KH, TDS and more in one quick sheet. Color-coded safe ranges tell you at a glance if something's drifting. Interactive charts show trends over weeks or years — with the safe zone drawn right on the graph and touch-to-read values on every point.

KNOW WHEN SOMETHING'S WRONG The home screen flags out-of-range parameters and overdue maintenance across all your tanks the moment you open the app — no drilling in required.

NEVER MISS A WATER CHANGE Set schedules for water changes, filter cleans, dosing, and trimming, with reliable local reminders at the time you choose. The built-in water change calculator tells you how much to pull, how much conditioner to add, and — the part nobody else answers — what the change will actually do to your nitrate, including the floor set by nitrate in your own tap water.

YOUR WHOLE TANK, REMEMBERED Livestock list with photos — fish, inverts, plants — searchable by species. A photo journal for milestones, rescapes, and diary notes, with full-screen pinch-to-zoom. Everything works offline.

HONEST PRICING Free forever: 1 tank, working reminders, 30 days of history, the full cycle tracker, and the calculator. TankDiary Pro unlocks unlimited tanks and full history as a one-time purchase. There's a cheap yearly option too, but we think you'll prefer to just own it.

No account. No cloud lock-in. No selling your data — there's nothing to sell; it never leaves your device.

Made by a hobbyist who got tired of spreadsheet water logs.

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