TankDiary: Aquarium Tracker

Tap the color square that matches your test tube and the reading is saved. Cycle tracker tells you the stage you're in and what to do next. No account needed.

Know when your new tank is safe for fish — TankDiary reads your ammonia, nitrite and nitrate tests and names the cycle stage you're in.

Log a water test by tapping the color that matches your test tube.

No account, no cloud, nothing leaves your phone.

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.

SPEAKS YOUR LANGUAGE Fully translated into German, Japanese and Brazilian Portuguese, with the terms hobbyists actually use. Units follow your region and can be changed anytime.

HONEST PRICING Free forever: 1 tank, working reminders, 30 days of history, the full cycle tracker, the color chart and the calculator. TankDiary Pro unlocks unlimited tanks and full history as a one-time purchase — pay once, own it forever. 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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