Privacy

Effective October 31, 2026.

Your tank log stays in this browser

• There's no account unless you turn on Cloud sync (below). Your tanks, readings, water changes, quarantine checklists, medicine courses and breeding log are kept in this browser's storage on this device. We don't receive them.
• Backup file: "Export backup" saves them to a file on your device. Where that file goes is up to you. "Import a backup" reads it back in this browser; it isn't uploaded. The backup file is free for everyone, with or without Pro.
• Reminders and notifications are worked out in this browser from your log. If you turn notifications on, your browser shows them; there's no push server, and we don't see them.
• Clearing this site's data in your browser deletes the log on this device. Keep a backup file if you want it back.

What reaches our server

• Your email address, only if you type it into "Save this forecast", together with that forecast: the tank details and readings in the form, and the forecast dates.
• A forecast count: each time you run a forecast, we record that one ran and the model version. Not your readings, unless you share a finished cycle (below).
• If you choose to share a finished cycle: when you mark a tank cycled, you can tap "Share this cycle". It's off unless you tap it, each time. We then receive: fishless or fish-in, the ammonia source and dose, any added bacteria, the tank type, a size band (under 40 L, 40–150 L, over 150 L), each reading's ammonia, nitrite, nitrate, pH, KH and temperature counted in days from the start (no calendar dates), the day it finished, our first forecast for it, the model version, and a random id so a re-send is kept once. Not the tank name, notes, your email or the cookie id. We store it with the day it arrived, not your IP address, and it's not linked to you. Because nothing links it back to you, we can't find it later to delete it. We use these cycles to check and improve the forecast dates.
• An anonymous cookie (cf_id): a random id, so we can count how many different people use TankTrue, or arrive through a partner link, without counting refreshes. We store only a scrambled (hashed) form of it. The cookie (cf_id) lasts a year. This id is never linked to your email.
• A partner cookie (tt_ref), only if you arrive through a partner's link (a fish store, club or creator): it holds that partner code and the date of your first click, and lasts 60 days. If you save your email in that time, we record that your sign-up was referred by that partner, so the partner can be paid. If you buy, the partner code goes to Stripe only, with your payment, so the sale is credited. Partners see counts, and the date, plan and amount of each payment, never your email or name.
• Your IP address, held briefly in memory, not on disk, to stop abuse (rate limits). We don't store it, but our hosting provider's logs may record it.
• Pre-orders: we record that the pre-order button was clicked and that a pre-order finished, with a short code for where you came from (for example a link we shared). Stripe handles the payment under its own privacy policy. We never see your card.

Cloud sync (Pro)

Cloud sync is off unless you sign in to it. Sign-in is a one-time link emailed to an address you've already saved with us; there are no passwords. Once you're signed in, we store:

• Your tank log: the last 3 copies your devices synced (each tank with the time it was last changed), so another device can pull it and you can go back to an earlier copy. Each copy is capped at 1 MB.
• Sign-in sessions: one per signed-in device, stored only in a scrambled (hashed) form, ending after 30 days or when you sign out. Your browser keeps the session in a cookie (tt_sync) that's only sent to our sync service.
• Used sign-in links: a random code from each link, so a link can't be used twice. Links expire after 15 minutes.

Sync only runs while you have Pro. If Pro ends, your stored copies stay until you delete them, and you can still download the latest one with the button below.

Delete your cloud data: the button below removes every stored copy from our database and signs out every device. Copies are removed from our database backups within 14 days, as those backups roll off. Your tanks on this device aren't touched. The Delete my data link in our emails removes it too.

What we do with it

• Email you your saved forecast; reminder emails are coming. A new address first gets one email with a confirm link; nothing else is sent to it until you tap that link.
• Count usage in aggregate. These totals (forecasts run, email sign-ups, pre-orders) are an admin-only count with no personal data in it. There are no ads, no trackers, and we never sell or share your data.

Unsubscribe or delete

Every forecast email has a one-click Unsubscribe link and a Delete my data link. Unsubscribe stops forecast emails; we still send renewal notices for a paid plan and sign-in links you ask for. Delete removes your email address, saved forecast, cloud copies and plan record for good. It doesn't cancel billing, so cancel your plan first. You can also email hello@tanktrue.com and we'll do it within 30 days. Shared cycles can't be deleted, because nothing links them to you.

How long we keep it

Your email, saved forecast, cloud copies and plan record stay until you delete them, or ask us to. Database backups roll off, and backups keep deleted data for up to 14 days. Shared cycles are kept to check and improve the model, since they can't be traced to you.

The fine print

• TankTrue is for people in the US and isn't meant for children under 13.
• If this policy changes, we'll update the date above, and email you first if the change affects data you've already given us.
• Questions: hello@tanktrue.com · TankTrue, [[POSTAL_ADDRESS]]