Aquarium water test log
One row per test. Ammonia and nitrite should read zero — write the number anyway.
| Date | pH | NH₃ (ppm) | NO₂ (ppm) | NO₃ (ppm) | Change % | Notes |
|---|---|---|---|---|---|---|
Targets NH₃ 0 ppm · NO₂ 0 ppm · NO₃ under 20 ppm before a change · pH stable
fishtankdiary.com/tools/printable-logThis is the version that does not need a battery. The sheet above is the same log the app keeps — date, pH, ammonia, nitrite, nitrate, water change and a note — except that nothing is typed in. You write with a pen, and the sheet waits by the tank until the next test.
How to use it
- Fill in the tank name, volume and month before printing, or leave them blank and write them in — both work.
- Print at 100%, not “fit to page”. The columns are sized for handwriting, and scaling them down is what makes a sheet unreadable.
- Use one row per test, and put the water change in the same row as the test that followed it.
- When the sheet is full, keep it. The value of a log is the comparison across months, not the latest number.
Choose “Save as PDF” in the print dialog to keep a digital copy. The layout is identical, and the sheet is a single page either way.
Why these four columns
pH, ammonia, nitrite and nitrate cover almost every freshwater problem. Ammonia and nitrite should read zero once the tank is cycled, so they are the fastest warning you have. Nitrate is the number that tells you whether the water change interval is right, which is why it goes on the sheet before the change rather than after.
| Column | What to write | Reference |
|---|---|---|
| Date | The day you ran the test | One row per test, not per day |
| pH | The number the kit gives | Stable matters more than “correct” |
| NH₃ (ppm) | Ammonia | 0 ppm in a cycled tank |
| NO₂ (ppm) | Nitrite | 0 ppm in a cycled tank |
| NO₃ (ppm) | Nitrate | Under 20 ppm before a change |
| Change % | Share of the water replaced | Write the litres in Notes if it helps |
| Notes | Feeding, behaviour, filter, new fish | The column you will actually reread |
Paper, browser or spreadsheet
If you would rather not print anything, the browser log takes the same four numbers and keeps them on the device, and the CSV template is for people who want a spreadsheet. The app is for reminders and trends.
