Tankmark – Aquarium Water Log

Unlimited readings. No monthly cap. No subscription — one purchase and it's yours. CSV in and out, so your log is never locked in an app. Tankmark is a water-parameter notebook for aquarium keepers. Log a test in seconds, see the trend, get a reminder, export everything. LOG IN SECONDS One sheet, numeric keypad, your parameters in your order. Skip anything you didn't test. Date defaults to now. YOUR BANDS, YOUR CALL Set a target range per parameter — or don't. The chart shades your band and colours the latest value in or out of it. Tankmark never tells you your water is "safe" or "dangerous" and never calculates a dose. It's a notebook, not a verdict. SEE THE TREND Latest value and sparkline for every parameter. Tap for the full chart with 7, 30, 90-day and all-time ranges. Water changes, doses, filter changes and new livestock show as markers on the chart, so you can see what changed after what. BUILT FOR YOUR TANK Freshwater, planted, saltwater and reef presets. Temperature, pH, ammonia, nitrite, nitrate, KH, GH, TDS, salinity, alkalinity, calcium, magnesium, phosphate. °F or °C, ppm or mg/L, dKH or meq/L, SG or ppt — switch any time, history converts with you. REMINDERS WITHOUT THE GUILT Test every N days, water change every N days. A missed reminder costs nothing and says nothing. YOUR DATA Everything lives on your iPhone and, if you turn it on, in your own iCloud. No account, no sign-in, no server of ours, no ads. Export any tank or all tanks to CSV from the share sheet. FREE, THEN PAY ONCE Free: two tanks, the last 30 days, reminders and CSV export. Tankmark Pro is one payment: unlimited tanks and history, every chart range, CSV import, all exports. No subscription exists. Questions or a parameter you're missing? hello@crusadi.org