Stablereef: Reef Tank Tracker
Saltwater aquarium test log
Free · Designed for iPad. Not verified for macOS.
Log every test in one quick session, get flagged on a rapid Alk swing, and enter the units your kit shows. Cycling a new tank? Ammonia & nitrite, front and center.
Stablereef is a fast reef tank tracker and water test log for saltwater aquariums. Log a full test in one quick session, catch a rapid Alk swing on the spot, and enter the units your test kit shows. Unlimited logging, CSV import and export — no account, no cloud, and no paywall in your core loop.
LOG A FULL WATER TEST IN ONE SESSION
Tap "Log a test session" and move through every parameter with a big number pad. Each step shows your last reading, only a rapid change stops you, and the rest lands in one summary where you can undo any single reading. Logging just one value? Tap its card and your last value is prefilled. Pin the parameters you test most and hide the ones you don't. No spreadsheet.
THE ANTI-SWING WARNING
Corals don't crash on a number; they crash on the swing. When you save a reading, Stablereef compares it to your last value — allowing for the time since that test — and flags a rapid change, like "Alk +1.3 dKH rapid change." Out-of-range readings are flagged too, using safe ranges re-checked against published reef guidance. You catch the risky move while you're still at the tank.
(Reference only — bands are tunable and husbandry calls are yours.)
ENTER THE NUMBER YOUR TEST KIT SHOWS
Track Alkalinity, Calcium, Magnesium, Nitrate, Phosphate, Salinity, pH and Temperature — plus Ammonia, Nitrite and Silicate when you need them — in the units your kit actually reads: dKH, meq/L or ppm (as CaCO3) for alkalinity; ppm PO4 or ppb P for phosphate (ppb P is what a Hanna HI736 shows); °C or °F; ppt or specific gravity. No converting in your head.
CYCLING A NEW SALTWATER TANK?
Turn on "This tank is still cycling" and Ammonia and Nitrite move to the front. While the tank cycles, high ammonia and nitrite readings get a calm "this is expected" note instead of an alarm, and Stablereef tells you when your readings suggest the cycle looks done.
SWITCHING APPS? BRING YOUR REEF LOG WITH YOU
Moving from another aquarium app or a spreadsheet? Import your history from any CSV, right from the first screen: automatic column detection, unit conversion (dKH, meq/L or ppm alkalinity; ppm or ppb phosphate; °F/°C; SG/ppt), a prompt when a column's unit is unclear, a preview before anything is written, and a clear report of exactly what came in. Import is free.
TRENDS, NOT JUST NUMBERS
7 / 30 / 90-day graphs with a shaded stability band let you separate real drift from noise and act before a small slip becomes a tank crash.
YOUR DATA IS YOURS
• CSV & JSON export, anytime — never behind a paywall
• Automatic local backups
• Works 100% offline — no account, no cloud, no sign-up
Want your years of history out? One tap. We don't hold your data hostage.
REMINDERS
Local notifications for dosing and testing keep you on schedule on the days you'd otherwise forget.
LOG AS OFTEN AS YOU TEST
Unlimited logging, anti-swing warnings, trends, reminders, import and export are free. No subscription, no monthly cap on readings, and no paywall in the middle of your core loop — ever.
THE "LESS" PHILOSOPHY
No livestock encyclopedia. No marketplace. No social feed. Stablereef does one thing — protect your reef tank's stability — and aims to do it better than apps juggling ten.
PRIVACY
No account. No cloud. No ads, no cross-app tracking. Your reef data stays on your device — the only thing we collect is anonymous usage counts, with no account, no personal data and no IP address, and you can switch that off in Settings.
WHO IT'S FOR
Reef keepers who want a focused saltwater aquarium log instead of a do-everything app: an alkalinity tracker that flags swings, a water test log that matches your test kit, and a simple way to track ammonia and nitrite while a new tank cycles. If you keep a spreadsheet today, we built this for you.
Reference tool only — not veterinary or husbandry advice. Stability bands are general references; care decisions are the keeper's responsibility.
From Sloth Lab Inc.
Ratings & Reviews
- This app hasn’t received enough ratings or reviews to display an overview.
Stablereef 1.2.5 — silicate, by request.
• NEW: Silicate, logged as ppm SiO2. It's off by default — turn it on in Settings → Parameters. The default range is 0–1 ppm (adjustable), and there's no rapid-change alert (silicate drops fast when diatoms use it up)
• CSV import reads Silicate, Silica and SiO2 columns. Values in ppm Si (for example from ICP) are converted to SiO2, and a column labeled just "Si" asks which one it is before importing. Silicate in AquaticLog exports is read as SiO2, and the result screen says so
Thanks to everyone logging with us — keep the feedback coming from Data → About → Send feedback.
The developer, Sloth Lab Inc., indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy .
Data Not Linked to You
The following data may be collected but it is not linked to your identity:
- Usage Data
Accessibility
The developer has not yet indicated which accessibility features this app supports. Learn More
Information
- Seller
- Sloth Lab Inc.
- Size
- 33 MB
- Category
- Utilities
- Compatibility
Requires iOS 15.0 or later.
- iPhone
Requires iOS 15.0 or later. - iPad
Requires iPadOS 15.0 or later. - iPod touch
Requires iOS 15.0 or later. - Mac
Requires macOS 12.0 or later and a Mac with Apple M1 chip or later. - Apple Vision
Requires visionOS 1.0 or later.
- iPhone
- Languages
- English
- Age Rating
4+
- 4+
- Copyright
- © 2026 Sloth Lab Inc.