About this app
What Tankbook does
Tankbook is the offline aquarium chemistry logbook for the 14.7 million US fishkeeping households. Built for the reef keeper who tests calcium, alkalinity, magnesium, nitrate, phosphate, salinity, and pH every week — and for the freshwater planted-tank owner whose parameters matter just as much. What ships in v1: — Ten-second entry sheet. The parameters you actually test, big number pads, swipe through. Done in under a minute, even with wet hands. — Trend charts per parameter. Swift Charts line graph for every value, last 7/30/90/365 days. Spot a slow alkalinity slide before it crashes a coral. — Multiple tanks. Reef display, freshwater planted, quarantine, frag tank. Each has its own parameters and its own history. — Test-kit reminders. Calcium every Tuesday. Alk every Friday. EventKit notification local to this device. — OCR for color cards (Vision). Snap a photo of an API test card or refractometer scale, Tankbook reads the value into the row. — PDF chemistry report. One-tap export to take to your local fish store or share with your reef-club mentor. — Equipment log. Skimmer, calcium reactor, dosing pumps — record when you last replaced media or carbon. — Livestock list. Per-tank fish + coral + invertebrate inventory with add date. — Stays on this phone. No account, no cloud, no analytics. Your tank, your data. — Free. The AquaticLog $25-a-year paywall on reminders ends here. For the reef keeper who's tired of the AquaPlanner data-loss horror stories, the Aquarimate UI from 2012, and the AquaticLog subscription gate.
Features
Built to be useful, not noisy.
Tank picker
Switch between reef/freshwater/quarantine tanks
Test entry
10-sec form for the week's parameters
Trend charts
Swift Charts per parameter, 7/30/90/365 days
OCR
Snap an API card or refractometer; VisionKit reads value
PDF report
Per-tank chemistry export via share sheet
Why it exists
The problem
Reef and planted-tank keepers test water chemistry weekly but every existing iOS app is broken (AquaPlanner data-loss horror stories), dated (Aquarimate 'UI feels designed in 2012'), or paywalled (AquaticLog $25/yr just for reminders).
What's different
How Tankbook stands out
Tankbook is the only iOS aquarium logbook with multi-tank support, per-parameter trend charts in Swift Charts, VisionKit OCR for API color cards and refractometer scales, and PDFKit chemistry-report export — all offline, no account, no $25/yr Pro tier — AquaPlanner lost users' years of data on an update, Aquarimate's…
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FAQ
Questions about Tankbook
How much does Tankbook cost?▾
Tankbook is free. All features are included from day one — no subscription, no in-app purchases, no paid tiers. Everything you see in this listing works the moment you install it.
Where does Tankbook store my data?▾
On your device. Tankbook is built privacy-first: no account is required, no analytics SDKs, no third-party trackers. Nothing is uploaded to a server we control — the app works without one.
What platforms does Tankbook support?▾
iOS, on iPhone and iPad. You can find the latest availability on this page.
How do I get support for Tankbook?▾
Use the Support link on this page, or email support@allthingsn.com. We answer every message and keep responses on the same thread.
The story
Meet Tankbook — Reef-grade water chemistry, on this phone
Read the full write-up · 4 min →
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