Hobbies & Makers · Mobile
TankLog: an aquarium water test log app that shows the trend
See the drift in your parameters weeks before the tank starts telling you about it.
TankLog is an aquarium water test log app for freshwater and reef keepers who test every week. It plots each parameter over time, so a slide in alkalinity or a nitrate climb is visible for a fortnight before the tank shows it the hard way.
Waitlist Not built yet Updated 5 September 2026
What problem does TankLog solve?
Nothing in a tank fails suddenly. Alkalinity slides for three weeks, or nitrate creeps up after you added two more fish, and the first sign anyone notices is a colony going pale or a fish breathing at the surface. By then the useful information is gone, because the only record of the last month is a test kit result you read in the kitchen and forgot on the way back to the tank. The scribbled version has the same hole. A notebook by the cabinet holds a column of numbers with no context: no note that you topped up with tap water that week, no note that the doser ran dry on the Thursday, no note that you changed salt brands. So when something goes wrong you have a snapshot and a guess. Reef keepers feel this hardest, because the parameters move together and the animals that suffer first are the slowest to come back.
Water parameter log
A printable month-per-page sheet for test results, water changes, and the notes that explain a change in the numbers.
| Date | Tank | Temp | pH | Ammonia | Nitrite | Nitrate | Water change and notes |
|---|---|---|---|---|---|---|---|
Free to use. No account. Nothing you type here is stored.
What would TankLog do?
TankLog would hold one log per tank and draw every parameter as a line rather than a number. You enter a test result in a few taps, and the app shows the last several weeks beside it, so a slow slide or a steady climb reads as a shape. Alongside the numbers you record the things that explain them: the water change and its volume, a new fish, a dosing change, a top-up with tap water, a heater swap. Those events appear on the chart as marks, so cause sits next to effect. Reminders cover water changes and test days on your own rhythm. TankLog never proposes a target value or a dose, because the right numbers depend on your tank, your livestock, and the system you chose to run.
How would it work?
- 1Set up a tank with the parameters you actually test, and skip the ones you do not.
- 2Enter a test result in a few taps, and see it land on the trend line.
- 3{'Mark the events that move numbers': 'water changes, new stock, dosing changes, top-ups.'}
- 4Set your own test and water change rhythm per tank, and let the reminders follow it.
Who is it for?
- Reef keepers running a mixed or stony coral tank who test alkalinity more than weekly.
- Freshwater keepers cycling a new tank and watching ammonia and nitrite for the first time.
- Anyone who lost livestock once and wants to see the next drift coming.
How do you keep an aquarium parameter tracker on paper that shows a trend?
Use one sheet per month with the dates running down the left and one column per parameter. That layout is the whole trick. A page per test gives you a stack of snapshots you will never compare, while a month on one page lets your eye do the work: the column that wanders is visible from across the room. Test at the same time of day, and write down which kit and which bottle batch you used. Reagents age, and a reading that moves the week you open a new kit is more likely to be the kit than the tank. If two kits disagree, note both readings rather than picking the one you prefer. Give the right-hand third of the sheet to events, not numbers. Water change with the volume. New livestock, with the date it went in. A dosing change and by how much. Top-up water source, especially if you used tap water while the unit was being serviced. Feeding changes. A heater or a pump that was replaced. Every one of those has moved a parameter for somebody, and none of them are recoverable from memory a month later. Once a month, sit with the sheet and read across, not down. You are not looking for a number, you are looking for a direction. Three readings drifting the same way matter more than one odd result, and one odd result surrounded by steady ones is usually a test error worth repeating before you act on it. Write a sentence at the bottom of the page saying what you saw. That sentence, twelve times a year, is the record that actually saves a tank.
What do people use today?
| Option | Good at | The gap |
|---|---|---|
| A notebook by the cabinet | Free, immediate, and it holds the odd note that no app has a field for. | A column of numbers on paper hides a slow drift, because you read the newest line and turn the page. |
| A spreadsheet with a chart | Real trend lines, your own parameters, and a chart you can paste into a forum thread. | Entry happens at a desk rather than at the tank, so readings queue up and some never get typed in. |
| Aquarium controller software | Logs temperature, pH, and ORP continuously from probes, with alerts when a probe reads out of band. | Covers only what a probe measures; alkalinity, nitrate, phosphate, and calcium still come from a test kit and your hand. |
| Photos of the test vials | Captures a color card comparison honestly, with a timestamp you did not have to write. | Color under kitchen light is not comparable week to week, and nothing turns a camera roll into a trend. |
| Build threads on hobby forums | Other keepers spot patterns in your readings and ask the question you did not think to ask. | Your history is scattered across replies, and nobody can chart it, including you. |
What would it cost?
Free
$0
- One tank
- Every parameter you test
- Printable log sheet
Keeper
$3.99/mo
- Unlimited tanks
- Trend charts over any date range
- Event marks for changes and dosing
- Test and water change reminders
Prices are proposed. Founding members lock in the lowest price if we build TankLog.
Questions people ask
What is an aquarium water test log app?
An aquarium water test log app stores the results of your test kits over time and shows them as trends rather than single readings. Alongside the numbers it records the events that move them, so a slide in one parameter can be matched to the week something in the tank changed.
Does TankLog tell me what my parameters should be?
No, and that is deliberate. Target values and safe ranges depend on your livestock, your system, and the approach you chose to follow. TankLog shows your own numbers moving and leaves the targets to you, your test kit instructions, and the keepers whose advice you trust.
Will it tell me how much to dose?
No. Dosing amounts depend on volume, current readings, consumption, and the product in your hand, and a wrong figure harms animals. You record what you dosed and when, and the log shows what happened next. The arithmetic and the decision stay with you.
Does it work for freshwater as well as reef?
Yes. You choose which parameters a tank tracks, so a planted freshwater tank can log ammonia, nitrite, nitrate, and pH while a reef tank adds alkalinity, calcium, magnesium, and phosphate. A tank never shows a field you do not test.
Can I log more than one tank?
Yes. Each tank keeps its own parameters, reminders, and chart, which matters when a quarantine tank and a display tank behave nothing alike. The free plan covers one tank, and the Keeper plan lifts the limit.
What happens to my readings if I stop paying?
Your log stays readable and exportable. TankLog would keep the whole history available as a spreadsheet download, because years of readings from one tank are worth more than a subscription and should never be held hostage.
When will TankLog launch?
There is no date. TankLog gets built only if enough aquarium keepers join this waitlist and say they would pay. Joining costs nothing, and the printable water parameter sheet on this page is yours either way.
Where does this stand?
TankLog is a proposal, not a product. This page collects demand from search and answer engines. Askwright builds it only if enough people join the waitlist and say they would pay. Read how this works.