Reef: Aquarium Chemistry Calc

Two-Part: Alkalinity & Calcium

Free · In‑App Purchases · Designed for iPad. Not verified for macOS.

Saltwater chemistry that pairs calcium and alkalinity the way the chemistry works. Magnesium-first guidance, daily-rise caps, dose history. No subscription. Reef is a chemistry calculator for saltwater reef-keepers. Log a test, get a dose. No accounts, no subscription, no ads. The dose engine pairs calcium and alkalinity the way the chemistry actually works. When you dose calcium with a two-part product, you have to dose alkalinity alongside it in matched volumes — otherwise the ratio drifts and you end up chasing one parameter while the other crashes. Reef sizes both doses together against your tested gap, your tank volume, and the specific concentration of the product you use (BRS Pharma, Aquaforest, ESV B-ionic, Tropic Marin All-For-Reef, or a custom product). Magnesium gets its own treatment. If your Mg sits below 1280 ppm, Reef tells you to fix that first — calcium and alkalinity won't stay in range without it. This is standard reef-keeping practice, but most calculators bury it. Doses are capped to safe daily rises (about 20 ppm Ca, 1.4 dKH Alk) so you don't crash the tank reaching for a target in a single day. Larger gaps get split across multiple days, with the schedule laid out for dosing pumps. Test history lives on a chart so you can see your alkalinity drift over weeks instead of guessing from memory. Dose history sits beside it so you can see what worked. Everything stays on your device. Reef has no internet connection, no analytics, no accounts. Buy it once. Built for mixed-reef, SPS, and LPS tanks.

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• The Pro screens are now translated. They were English-only in every language the app ships — including yours. • Store listing corrected: the app is free with an optional one-time unlock, and no longer advertises an old price.

Version 1.4

The developer, Roman Kopaliani, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy .

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    Information

    Seller
    Roman Kopaliani
    Size
    992.3 KB
    Category
    Utilities
    Compatibility
    Requires iOS 17.0 or later.
    • iPhone
      Requires iOS 17.0 or later.
    • iPad
      Requires iPadOS 17.0 or later.
    • Mac
      Requires macOS 14.0 or later and a Mac with Apple M1 chip or later.
    • Apple Vision
      Requires visionOS 1.0 or later.
    Languages
    English and 5 more
    • English, French, German, Italian, Portuguese, Spanish
    Age Rating
    4+
    In-App Purchases
    Yes
    Copyright
    © 2026 Roman Kopaliani
  • Privacy Policy

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