Last updated: 4 October 2026
This is an English translation for convenience. The German version is the legally binding one.
1. What this is about
reefnotes (reefnotes.com) is a free aquarium logbook: you record readings, water changes, fertiliser doses and plans for your tanks, and reefnotes keeps them, shows trends and gives hints. reefnotes is run as a private hobby project by Rafael Fuchs (contact details in the imprint). There are no ads, no paid tiers and no sale of data — how your data is handled in detail is described in the privacy policy.
By creating an account you agree to these terms. The freely accessible calculators, guides and reference pages can be used without an account; sections 5 and 6 apply to them accordingly.
2. Account and minimum age
reefnotes is meant for people aged 16 and over. If you are younger, we need the consent of a parent or guardian before you create an account (Art. 8 GDPR).
You create your account with a valid email address and keep your password secret. You are responsible for what happens through your account — if you suspect someone else has access, change your password in your profile and let us know. One account per person is enough; creating accounts for other people's email addresses is not allowed.
Until you confirm your email address, your account is on probation: you can use reefnotes normally for seven days, after which confirmation is required to keep signing in. Accounts that were never confirmed and contain no tank are deleted automatically after 30 days.
3. What reefnotes does — and what it doesn't
reefnotes is free and provided as is. I work to keep everything running reliably, but as a hobby project I cannot promise any particular availability, freedom from errors or the permanent continuation of individual features. Features may change or be removed. Should reefnotes ever be shut down, I will announce it by email with reasonable notice so you can export your data first.
Your data belongs to you. You can export all of it from your profile at any time (JSON) and delete your account yourself at any time.
4. Your content
What you enter in reefnotes — readings, notes, photos, tank descriptions — remains yours. You only grant reefnotes the right to store this content, show it to you and process it as needed for the service (for example for trends, forecasts and the Sunday issue).
If you share a tank publicly, the shared content is visible to anyone with the link. Only publish photos and texts you hold the rights to, and nothing that infringes the rights of others or breaks the law. I may remove such content; in case of abuse (such as spam, attacks on the service or creating accounts for others) I may block or delete an account.
5. Important: water parameters and dosing
reefnotes calculates with the values you enter. Forecasts, ranges and dosing suggestions are guidance, not instructions. They can be wrong — because a test kit was inaccurate, a value was mistyped, the tank behaves differently from the model, or the model simply has its limits.
Animals and plants live in your tank. You decide what you dose. Follow the manufacturers' instructions, change values slowly, watch your animals and get expert advice when in doubt. reefnotes replaces neither experience nor expert advice — it helps you keep track.
6. Liability
For a free service: I am liable without limitation for intent and gross negligence and for damage arising from injury to life, body or health. For simple negligence I am only liable for breach of essential contractual obligations, and then limited to the foreseeable, typical damage. Beyond that, liability is excluded — in particular for damage to animals, plants or equipment arising from the use of forecasts and dosing suggestions (see section 5), and for loss of data where you failed to take reasonable precautions of your own (export). Statutory consumer rights remain unaffected.
7. Ending
You can delete your account in your profile at any time — no notice period, no questions asked. What then happens to your data depends on your "help reefnotes learn from my data" setting and is described in the privacy policy. I may delete accounts in case of abuse (section 4) or after prolonged, unconfirmed inactivity (section 2).
8. Changes to these terms
As reefnotes evolves, these terms may change too. I will inform you of material changes by email or at your next sign-in, at least two weeks before they take effect. If you do not agree, you can delete your account before then; if you keep using reefnotes afterwards, the new terms apply.
9. Final provisions
German law applies. If you are a consumer living in another EU country, the mandatory protective provisions of your country of residence remain available to you. I am neither obliged nor willing to take part in dispute resolution proceedings before a consumer arbitration board. Should any provision be invalid, the rest remains valid.