My tanks
Keep a simple log for each aquarium: its fish, water test results, cycle status and maintenance reminders. Everything stays in this browser.
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Your tanks
My tanks keeps a record of each aquarium you own: the fish in it, your water test results, whether it's cycled, and reminders for water changes and filter care. It warns you when a reading is unsafe for your fish. Nothing is uploaded and there's no sign-up.
Back up or move your tanks
Your tanks live only in this browser. Download a backup file every few weeks, and import it to restore your tanks or move them to another device. Importing adds the tanks in the file and replaces any with the same ID. It never deletes your other tanks.
Log a water test
Maintenance
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Test history
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| Date | Ammonia | Nitrite | Nitrate | pH | Temp | GH | KH | Note | Actions |
|---|
Fish and stocking
No fish yet. Add the fish you have, or plan to keep, in the stocking calculator to check stocking and compatibility.
Tank details
My tanks is a free aquarium log that runs in your browser. Save each tank, log ammonia, nitrite, nitrate, pH and temperature, see whether the tank is cycled and which readings are unsafe, and get reminders for water changes and filter care. Your data never leaves this device.
Your data stays in this browser
There is no account and nothing is uploaded. My tanks saves everything in your browser's local storage on this device. That keeps it private, but it also means:
- Clearing your browsing data, or using a private window, removes your tanks.
- Your phone and your computer each keep their own copy.
To keep your records safe, open Back up or move your tanks above the list and download a backup file every few weeks. To move to another device or browser, import that file there.
What the readings mean
| Reading | Aim for | Act when |
|---|---|---|
| Ammonia | 0 ppm | 0.25 ppm: change 25–30% of the water and feed lightly. Above 0.25 ppm, or any reading at pH 8 or higher: change 30–50% today |
| Nitrite | 0 ppm | 0.25 ppm: change 25–30% of the water. Above 0.25 ppm: change 30–50% today |
| Nitrate | Under 20 ppm | Above 40 ppm: change water more often. Above 80 ppm: lower it over a few days |
| Temperature, pH, GH | Inside the range all your fish share | Outside it: adjust slowly |
| KH | 3 dKH or more | Under 3 dKH: pH can swing, so test it more often |
A tank is cycled when ammonia and nitrite read 0 and nitrate is above 0, on two tests taken on different days. With no fish in the tank, ammonia and nitrite are expected while it cycles, so they are shown as notes rather than warnings. If ammonia is 1 ppm or more and pH is below 6.5, change only 10–25% a day, because a big change raises the pH and makes the ammonia more toxic. The ammonia guide explains why. Our guide on how to cycle a fish tank explains the steps. The fish ranges come from our species profiles, and the stocking level comes from the stocking calculator (how it works).
Frequently asked questions
Where is my tank data stored?
Only in this browser on this device, in its local storage. There is no account and nothing is uploaded. Clearing your browsing data or using a private window removes it, so download a backup now and then and keep the file somewhere safe.
How do I know if my tank is cycled?
Log a test with ammonia, nitrite and nitrate. When ammonia and nitrite both read 0 and nitrate is above 0, the filter bacteria are processing waste, so My tanks shows "Looks cycled". A second clean reading on a later day confirms it and the badge changes to "Cycled". Any ammonia or nitrite above 0 means the water is not safe yet.
Can I use My tanks on my phone and my computer?
Yes, but each browser keeps its own copy. Download a backup on one device and import it on the other. Importing adds the tanks in the file and replaces any with the same ID. It never deletes your other tanks.