Tank Notes: Water Test Log

Tank Notes is a private logbook for aquarium water tests. Write down what your kit says, and it tells you whether those numbers are safe for the fish that actually live in that tank, not for a generic chart.

• ONE LOG PER TANK
Freshwater, planted or saltwater. Log pH, ammonia, nitrite, nitrate, temperature, carbonate hardness and, for saltwater, salinity. Fill in only what you tested that day. Swipe any test to duplicate or delete it.

• RANGES THAT FOLLOW YOUR FISH
Add the species in each tank. pH and temperature limits become the range where all of their needs overlap, so a tank of neon tetras, corydoras and shrimp is judged differently from one with a betta. If your species do not overlap at all, Tank Notes says so instead of guessing. Every reading is marked OK, Watch or Alert, with a word, never colour alone.

• SEE NITRATE COMING
The Trends tab plots any parameter against the safe band for that tank, with your water changes marked. For nitrate, it follows the slope since the last change and tells you roughly when it will cross the line.

• THE NEXT WATER CHANGE
Set how often and how much you change. Care shows what is due, keeps a history of changes, filter rinses and glass cleaning, and has a calculator for how much to replace to bring nitrate down to a target, allowing for nitrate in your tap water. An optional reminder arrives at 9:00 on the day. It is a local notification and is only requested if you switch it on.

• METRIC OR US UNITS
°C or °F, litres or gallons. Readings are stored in °C, so switching never changes your data.

• OFFLINE AND PRIVATE
No account, no ads, no analytics, no internet connection. Export your tests to CSV whenever you want a copy.

Species ranges are general care guidance, not veterinary advice. Test kits differ.