Atoll — Aquarium & Reef Log

NRD Studio ID

In-app purchases

About this app

Atoll is an offline-first log for reef and freshwater aquariums.

Every reading you take lives on your phone. No account, no sign-up, and nothing to lose when the network is not there — which, for most people, is exactly where the tank is.

It tells you what happens next

Log a few tests and Atoll fits a line through them. When a parameter is drifting steadily towards the edge of your target range, it says so, and how many tests over how many days that is based on, so you can weigh it yourself. With Pro it also tells you when it will get there, how fast it is moving, and draws the projection on the chart.

It stays quiet when your tank is simply steady, when there are too few tests to be sure, or when the readings are too scattered to say anything honest. A warning you can trust is one that is not always on.

Ten-second logging

A purpose-built keypad instead of a form. Your previous reading sits beside what you type and the target band lights up as you go, so a wrong number is obvious before you save it.

The numbers that matter, not the ones on the box

Tell Atoll about your sump and roughly how much rock and sand you have, and it works out how much water your tank actually holds. A reef packed with rock can hold 15% less than its rating — and that difference is the whole of a dosing error.

Everything in one timeline

Tests, water changes, doses, tasks, photos, and what happens to your livestock, in the order it happened.

Also included

• Charts with your target range drawn behind them, and the trend carried forward
• A dose calculator that works from the water your tank actually holds
• Recurring tasks on a real schedule, that record the job and not just the tick
• Livestock, with what arrived and what did not make it
• Photos, because growth and colour are the two things a number cannot show you
• Reef, saltwater, freshwater, planted and brackish tanks

What we commit to

Recording your results, seeing every chart, and exporting your own data are free, forever, on every tank. Most aquarium apps charge to sync your own data; we think the log you typed belongs to you. Pro adds more tanks and the forecast's countdown — monthly, yearly or as one lifetime payment — and never takes away something that was already free.

Atoll does not use AI, and nothing in it is a guess dressed up as one. The forecast is a straight line fitted to your own results, and it refuses to draw one when those results cannot support it.

Currently in English.

What’s new

Atoll Pro can now be bought once, for life, as well as monthly or yearly.

With Pro, the forecast says how many days a drifting parameter has and how fast it is moving, and the chart shows where it is heading.

The free plan now covers one tank. Logging, charts, history, export and the warning when a parameter heads out of range stay free, forever.