Aquarium water test tracker

Your reef's history can never be wiped.

Log every water test, watch trends against safe ranges per tank, and get a conservative next step when something drifts — offline, on your device, forever.

Works offline · No account · One-time $11.99 · Export anytime

Works offline
No account
One-time price
Your data is yours (export anytime)

Features

Built around one number: what changed since last test.

Event markers on every chart

Water changes, doses, and filter cleans plotted right on the trend line, so cause and effect is visible at a glance — not buried in a log.

Conservative dose advisor

Alk 7.2 → target 8.4 dKH: dose 18 ml for your 75 gal, re-test in 24h before dosing again. Always shows the math. Never chains doses without a re-test.

Parameter tiles at a glance

Green in-range, amber drifting, red out — with the arrow versus your last test, for every parameter that matters to your tank type.

Tuned to freshwater or reef

Freshwater tanks track pH, ammonia, nitrite, nitrate. Reef tanks add alk, calcium, magnesium, salinity, phosphate. Pick a preset, get the right grid.

Trend charts with safe-range bands

1M/3M/1Y views per parameter, with the safe range shaded so you can see drift building before it becomes a problem.

Multiple tanks, one app

Name, type, volume, photo — switch between every tank you keep, each with its own history that stays on your device.

Pricing

Pay once. Keep it forever.

Free

$0

1 tank, core parameters.

  • pH, ammonia, nitrite, nitrate
  • Status tiles with in-range/drifting/out
  • Log tests and events

Pay once. Keep it forever. No subscription.

FAQ

Questions

Does TankLog work offline?

Yes. Every test, trend, and reminder lives on your device. No internet connection required, ever.

Do I need an account?

No. There's no sign-up, no login, and no cloud sync of your data.

Is this a subscription?

No. One payment of $11.99 unlocks unlimited tanks and every feature, for as long as you use the app.

Can I get my data out?

Yes. Export any tank's full test history to CSV whenever you want.

What platforms are supported?

iPhone and iPad, running current iOS.