For journalists, bloggers, YouTubers, podcasters, and reef-community sites. Everything you need to write or talk about Reef Monitor.
Reef Monitor is a free, offline iPhone app for tracking saltwater aquarium water parameters. Built-in Salifert test-kit timers, alkalinity consumption rate, NO3:PO4 ratio detection, multi-tank support, 15 languages. No ads, no account, no tracking. Built by a reef keeper, for reef keepers.
Reef Monitor is a free iPhone app that helps saltwater aquarium hobbyists log water parameters quickly and spot drift before it harms their corals. It includes built-in Salifert test-kit timers (30-second shake plus 3-minute wait for nitrate; 30-second shake for phosphate), an alkalinity consumption rate calculator that surfaces dKH/day uptake (a key SPS health signal), and automatic NO3:PO4 ratio and Ca/Alk/Mg ionic balance detection. The app supports unlimited tanks, 15 reef parameters (water chemistry and nutrients), and dosing logs that overlay onto trend charts. Data is stored entirely on-device in SQLite. There is no account, no cloud, no analytics, no tracking, and no internet requirement at all. Reef Monitor is 100% free with no in-app purchases or subscription, available in 15 languages, and built by one reef keeper for the reef community.
Reef Monitor is a free, offline-first iPhone app designed for saltwater aquarium hobbyists who manually test their tank water and want a fast, wet-hands-friendly way to log readings, spot trends, and catch parameter drift before it damages livestock. The app is unique among saltwater trackers in three ways. First, it includes built-in Salifert test-kit timers (the dominant manual-test brand in the reef hobby): a 30-second shake timer plus 3-minute wait timer for nitrate, and a 30-second shake timer for phosphate, with progress bars and haptic feedback. Second, it surfaces an alkalinity consumption rate (dKH/day) calculated via linear regression on recent readings, a signal that SPS keepers rely on to spot acidification trouble early. Third, it automatically watches the NO3:PO4 ratio and Ca/Alk/Mg ionic balance and alerts the user when they drift outside healthy bounds. Reef Monitor supports unlimited tanks, with each tank holding its own readings, alert thresholds, dosing log, and water-change log. Users can track up to 15 parameters covering both water chemistry (temperature, salinity, pH, alkalinity, calcium, magnesium, potassium, strontium, iodine, boron) and nutrients (nitrate, phosphate, ammonia, nitrite, silicate). Dosing entries appear on the trend charts they affect, so the impact of every correction is immediately visible. The app runs entirely offline: data is stored locally in SQLite, there is no account or sign-in, and Reef Monitor makes zero network requests. Analytics, tracking, and advertising SDKs are absent by design. CSV export and import are built in for user-controlled backups. Reef Monitor is 100% free with no in-app purchases, no subscription, and no premium tier. It supports 15 languages out of the box. The app is built and maintained by Nicolas Bertrand, a French reef-keeper, as an open-source project under the MIT license.
Email: delegue.grs@gmail.com. Response within 48 hours for press inquiries.
Last updated: 2026-06-03
