Product
In developmentReefChronicles
A reef tank is a chemistry problem that runs around the clock. ReefChronicles is the logbook that does the arithmetic — it reads your tank’s consumption rate out of your own test history and tells you what to dose.
The whole product, in one sentence
Every reefer asks the same question.
How much do I need to dose per day? The honest answer depends entirely on their tank, this month, at this coral load — and it is a regression over their own test history minus the doses they logged.
That is a short function. Nobody ships it. Existing apps are free-with-ads and abandoned, or they come from a supplement manufacturer and only know that manufacturer’s products.
At your current dose of 30 mL/day you are falling behind by 0.11 dKH/day. Raise to 38 mL/day to hold steady.
- READINGS
- 9
- INTERVALS USED
- 7 of 8
- METHOD
- Median
- EFF. VOLUME
- 372.7 L
The engine
Six decisions.
Each one is somewhere this could quietly produce a wrong number. All of it runs on the phone — no network, no API, no per-user cost, which is also why it works in a fish room with no signal.
- 01
Effective volume, computed once and shown to you
Every dose is scaled by how much water is actually in the system, so if that number is wrong every dose is wrong by the same factor, forever, and silently. The setup wizard takes the display and the sump at its operating level — never its nameplate capacity — then subtracts what the rock and sand displace. It shows you the result and lets you overwrite it, because someone who filled their tank with a measured bucket has better data than any formula.
- 02
Consumption rate, as a median over your own intervals
Between any two tests, what the tank consumed is what your doses should have added minus what actually changed. Do that across a 21-day window and take the median — not the mean, because hobby test kits read in 0.1 to 0.5 dKH steps by colour match under bad light, and one mis-read titration would wreck an average. Intervals under 24 hours are discarded, so is any interval containing a water change over 5%.
- 03
It says “not enough data” instead of guessing
Nothing is reported below four readings and seven days of span. Confidence comes from median absolute deviation rather than standard deviation, for the same reason the estimate itself is a median. And when there is not enough to answer, the app says what would fix it — “test twice more this week” is actionable in a way that “insufficient data” is not.
- 04
Potency derived from chemistry, not from a brand
For a pure compound, how much one gram moves one litre follows from molar mass. Soda ash is 52.836 dKH per gram per litre; baking soda is 63.1% of that; anhydrous calcium chloride is 32.5% stronger than the dihydrate, which is exactly the water-of-crystallisation difference. Arithmetic anyone can recheck, needing no manufacturer’s cooperation and unable to go stale. Proprietary liquids are derived from the maker’s own published dosing instructions, with the quote and the working stored alongside the number.
- 05
The unsafe answer is never the headline
Corrections are capped at what corals can absorb in a day, and the result type has no field a screen could bind as an uncapped number — enforced structurally, not by convention. Over the cap you are shown the safe daily amount, how many days it will take, and why in plain language. Products that move more than one parameter are capped against every parameter they move, since a calcium correction that is fine for calcium is the one that drags alkalinity past its limit.
- 06
The salinity error nobody tells you about
A refractometer calibrated at 20 °C, read at tank temperature, comes back low by around 0.0015 SG — roughly 2 ppt. The instrument agrees with itself every time, so a lot of tanks run at the wrong salinity for years. Setup asks which standard your tool uses and corrects silently. Beyond a ±10 °C offset it returns the reading untouched and says it cannot correct it, rather than implying no correction was needed.
Safety limits
The caps are not configurable.
Maximum change the app will recommend in twenty-four hours. They apply by magnitude — dropping alkalinity four points is as dangerous as raising it four. Parameters with no published limit say so, which is not the same as saying they are safe to swing.
A keeper who doses a full correction in one go can lose a tank. That is the whole reason this table exists.
- Alkalinity
- 1.4 dKH
- Calcium
- 50 ppm
- Magnesium
- 100 ppm
- Salinity
- 0.001 SG
- Temperature
- 1 °C
- pH
- 0.2
What costs money
Free records. Pro explains.
One rule, applied everywhere: anything that captures data is free, forever, with no limit. Anything that interprets data across time is the paid tier.
So unlimited tanks, unlimited parameter logging, your full history and charts, task reminders, the dosing calculator with its safety limits, consumption between any two tests worked out by hand, custom products, equipment tracking, CSV in and out, and cloud backup are all free. There is no one-tank cap, because a spreadsheet does not have one either and paywalling storage just invites the comparison.
The subscription buys the consumption-rate engine running continuously, the predictive alerts built on it, a maintenance dose personalised to your tank, multi-parameter charts, and “what changed?” analysis.
At a glance
- Platform
- iPhone, native Swift
- Android
- After the iPhone release
- Status
- In development — not released
- Engine
- Runs on device. No network, no API
- Account
- Optional. Fully usable without one
- Data
- CSV export and in-app account deletion
Where it stands
It isn’t finished, and it isn’t for sale.
ReefChronicles is being built now. There is no release date and no App Store listing yet, and this page will say so until there is. If you keep a reef tank and want to be told when there is something to test, write to us and we will put you on the short list — no newsletter, and we will not use your address for anything else.