Terms of Use
These terms govern your use of the app. Section 6 is the one that matters most, and it is written plainly rather than defensively: this app calculates, it does not measure, and carbon dioxide is genuinely dangerous to the animals in your tank.
01Scope and provider
The app “CO2 Calculator: Planted Tank” (referred to here as CO2Scape) is provided by Levin David Schwab, sole proprietor, Germany, contact levin.schwab@gmx.de. These terms apply between you and me for the use of the app and of this website.
The app is distributed through Apple’s App Store. Apple’s Licensed Application End User License Agreement applies in addition; where it conflicts with these terms, the more specific provision of Apple’s agreement governs the distribution relationship, while the provisions here govern the app itself. Apple is not a party to these terms and is not responsible for the app or its content.
02What the app does, and what it does not do
CO2Scape computes an estimate of the concentration of dissolved carbon dioxide in aquarium water from three values that you enter: carbonate hardness, pH and temperature. It applies the carbonate equilibrium relation with the temperature-dependent first dissociation constant of carbonic acid, and it reports the result as an interval derived from the measurement tolerances you declare. Two further paths are available that need no carbonate hardness value at all: the difference between the pH of a degassed sample and the pH of the tank, and the reading of a drop checker filled with a reference solution. Alongside that the app converts hardness units, computes a net tank volume and a fertiliser dose, lets you log pH readings through a photoperiod, and stores the readings you save on the device.
Understand precisely what that means:
- The app contains no sensor and performs no measurement. It has no way of observing your tank. It reads only what you type.
- The output is a model result, not an observation. If an input is wrong, the output is wrong, and it will still look entirely plausible.
- The underlying method is valid only where the carbonate system alone determines pH. The app asks about known interfering substances and blocks the calculation when one is declared, but this check depends entirely on your declaration being accurate and complete. It cannot detect a substance you did not disclose.
- The app is not a measuring instrument within the meaning of measurement law, not a medical or veterinary device, and not a substitute for observing your livestock.
03Licence to use the app
You receive a simple, non-exclusive, non-transferable right to install and use the app on devices you own or control, for private or commercial purposes, for the duration of these terms. You may not decompile, disassemble or reverse engineer the app except to the extent that mandatory statutory law expressly permits it (in particular §§ 69d, 69e UrhG), and you may not redistribute it, sublicense it, or circumvent the technical measures that gate purchased functionality.
04CO2Scape Pro and the in-app purchase
The app can be extended by the in-app purchase CO2Scape Pro at EUR 6.99, one purchase in the App Store. It is a non-consumable product, eligible for Family Sharing where you have enabled it, and it unlocks four things: an unlimited number of tank profiles instead of the single one the free app keeps, an unlimited measurement history instead of the last 30 saved readings, reminders at an interval you choose while a pH session is running, and export of your saved readings as a CSV file. There is no recurring charge and no renewal.
The purchase contract is concluded with Apple, which acts as the seller of record and handles payment, invoicing, taxes and refunds. I receive no payment data. Requests concerning billing or a refund go to Apple via reportaproblem.apple.com; the applicable terms are those of the App Store, together with any statutory rights you have as a consumer against Apple. Restoring a purchase on a device signed in to the same Apple Account is done from within the app.
Apart from Apple’s StoreKit interface, which is what makes the purchase and its restoration possible at all, the app integrates no third-party component and opens no network connection of its own. What happens to the values you enter is set out in the privacy policy.
05Your responsibilities as a user
- Enter values that you have actually measured, with instruments that are in working order and, where applicable, calibrated.
- Declare your substrate and any additives honestly. The validity checks exist to protect your animals; defeating them by mis-declaring a tank defeats the point of the app.
- Verify a computed result against an independent indication before you act on it: a drop checker filled with a reference solution of known carbonate hardness, the degassed-sample comparison, or simply the behaviour of your livestock.
- Increase carbon dioxide injection gradually and observe the tank afterwards. Never raise injection at night, and never leave a newly increased rate unobserved.
- Maintain the mechanical parts of your setup: the regulator, needle valve, solenoid, timer and diffuser. A calculation cannot compensate for a valve that fails open.
06Safety and liability
The honest version, first
Excess dissolved carbon dioxide kills fish and invertebrates. It lowers the pH of the water and impairs the ability of the animals to release carbon dioxide across their gills, which suffocates them even where oxygen is plentiful. Depending on the tank and the rate of injection, this can happen within hours, and the first visible sign, animals gasping at the surface, is already late.
CO2Scape reduces one specific risk: acting on a number whose uncertainty or invalidity you were not shown. It does not reduce the underlying risk of injecting carbon dioxide into a tank containing living animals. The responsibility for what you dose remains entirely yours.
Scope of my liability
I am not going to claim that all liability is excluded. Under German law such a claim would be void anyway, and it would be dishonest.
- I am liable without limitation for damage arising from injury to life, body or health, for damage caused intentionally or by gross negligence, in cases of fraudulent concealment of a defect, where I have given a guarantee, and under the mandatory provisions of product liability law.
- In cases of slight negligence, I am liable only for the breach of an essential contractual obligation, meaning an obligation whose fulfilment makes the proper performance of the contract possible in the first place and on whose observance you may regularly rely. In that case liability is limited to the damage that is foreseeable and typical for this kind of contract.
- Any further liability for slight negligence is excluded.
- These limitations apply equally to my personal liability as an entrepreneur and to persons whose conduct is attributable to me.
What is specifically not warranted
I do not warrant that a calculated value or interval corresponds to the actual concentration in a particular aquarium. The result depends on inputs I cannot verify, on measurement equipment I have no access to, and on the assumption that no undeclared substance influences the pH of your water. This is not a disclaimer bolted on at the end; it is the reason the app reports intervals and blocks results in the first place.
I also do not warrant that the app runs without interruption or defect, that it is compatible with every future version of iOS, or that a particular result will be reproduced by a different method or a different tool.
Where a defect in the app does exist, the statutory rules on defects in digital products (§§ 327 ff. BGB) apply unchanged. Report a defect to levin.schwab@gmx.de; I will treat a substantiated report as a bug and, where I can, fix it in an update.
07Availability, updates and discontinuation
The app runs entirely locally, so it works whether or not you have a network connection; the only situation in which connectivity matters is the purchase or restoration of CO2Scape Pro, which is handled by the App Store. Updates are delivered through the App Store and may change, extend or remove functions, in particular where a change is required to keep the app working on a new version of iOS or to comply with platform rules.
Should I discontinue the app, the copy already installed on your device continues to work for as long as your operating system supports it, and the data on your device remains yours. Because nothing is stored on a server, no shutdown of mine can take your measurement history away from you.
08Intellectual property
The app, its source code, its user interface, its texts, its icon and this website are protected by copyright and remain with me. The underlying chemistry is not: the carbonate equilibrium relation and the dissociation constant after Harned & Davis (1943) are published science, cited in the app precisely so that you can verify it independently. Data you enter and export remains yours; I claim no rights in it.
09Changes to these terms
These terms may be amended where the app changes, where the legal position changes, or where platform requirements change. The version published here at the time of your use applies, with the revision date stated at the top. Changes that materially disadvantage you will not be applied to a purchase already made without your agreement.
10Applicable law and dispute resolution
The law of the Federal Republic of Germany applies, excluding the UN Convention on Contracts for the International Sale of Goods. If you are a consumer with your habitual residence in another state, this choice of law does not deprive you of the protection of the mandatory provisions of the law of that state.
I am neither obliged nor willing to participate in dispute resolution proceedings before a consumer arbitration board within the meaning of § 36 VSBG. Your right to bring a matter before the competent courts is unaffected.
Should an individual provision of these terms be or become invalid, the validity of the remaining provisions is unaffected; the statutory rules take the place of the invalid provision.