# AquaCalculator — aquarium app for aquarists

> Aquarium management and documentation tool for marine and freshwater aquarists. (iPhone/iPad app by Michel Mohrmann.)

- Source: https://appshunter.io/ios/app/aquacalculator/id1449511522 (this page in markdown: same URL + `.md`)
- Developer: [Michel Mohrmann](https://appshunter.io/developer/544488594)
- Category: Productivity, Utilities
- Price: Free with in-app purchases
- Rating: 3.67/5 from 12 App Store ratings · 9 written reviews indexed
- Age rating: 4+
- Requires: iOS 18.6 · 49 MB
- Languages: Dutch, English, French, German, Italian, Polish, Chinese, Spanish, Swedish
- Released: 2019-02-20
- Data updated: 2026-07-07
- Monetization: subscription
- User reviews in markdown: https://appshunter.io/ios/app/aquacalculator/id1449511522/reviews.md

## What is AquaCalculator?

The reference software for dedicated marine aquarists

The AquaCalculator is not free. In order to be able to use the AquaCalculator permanently, you must complete a paid subscription after two weeks. In the first two weeks, the AquaCalculator can be tested for free and the subscription can be stopped at any time before it is chargeable.

The app for documentation and management of your aquarium. The main focus is on saltwater aquariums but also their freshwater pools can of course be documented with the AquaCalculator.
With the AquaCalculator you have the suitable manager at your fingertips to keep an eye on all important parameters regarding the care of your aquarium.

A big request: unfortunately we can not respond to reviews. If you have problems with the app, please contact us via email shortly (Support). So far we could clarify every question :-)

The reference software for every dedicated marine aquarist:

- Manage several basins in parallel

- Documentation of the water values ​​in graph and table form per pool. You can document your water readings, take notes or deposit pictures. The pictures can also be commented on.

- Animal Administration. You can also assign notes and pictures to your animals in the basin and thus get a quicker overview of the development of their stock.

- Dates: Management of recurrent memories help to keep track of the care of aquariums

- Realistic estimation of the required salt quantity of commercially available sea salt mixtures.
How much salt is actually needed to "adjust the salt content" or for the next "water change"? AquaCalculator calculates this using self-determined measurements of almost all commercially available sea salt mixtures.

- Addition of nutrients (nitrate and phosphate)

- Calculator to adjust calcium / alkalinity / magnesium: Expensive special agents are passé. AquaCalculator calculates the exact dosing quantities and stock solutions required for the adjustment of calcium, alkalinity (KH) and Mg concentration of low-cost salts.
Supports recipes from Aquafair, Aquaforest, Coral-Care, Fauna Marin, MT Aquaristics, Nyos, H.W. Balling, Price Aquaristics, A.Glaser, Red Sea, Sangokai, Tropic Marin, Fritz ProAquatics, Two Little Fishies, Kent Marine, Seachem, Brightwell, Continuum Aquatics, ESV and Self-Defined.

- Extensive setting options for the measuring instruments used, as well as the chem. Recipes.

- Mini-FAQ: answers the most important questions about adjusting the water values ​​and thus the successful care of reef aquariums. Including ten thousand times downloaded seawater FAQs by Martin Kuhn (Water Parameter FAQ, Anemone FAQ, Plague Master FAQs 1 and 2)

NOTE: We have provided iBooks from Apple for viewing the Seawater FAQs. The ad must have iBooks or another PDF viewing app installed on your device.

To use the AquaCalculator you must have a valid subscription.
This will enable you to take full advantage of the Aquacalculator, benefit from regular updates and enhancements, secure data storage and synchronization of your data with other devices.
Without a valid subscription, you can only read but not modify your data.
The term is one year.
Payment will be made through your iTunes account.
The subscription will automatically renew if it is not canceled 24 hours before the end of the current period.
Within 24 hours before the end of the current period, the amount for the renewal will be charged.
Termination of automatic renewal is possible at any time.

Terms of Use (EULA): https://www.apple.com/legal/internet-services/itunes/dev/stdeula/
Terms of Use and Privacy: https://acalc.de/pages/impressum

## Key features

- Manage multiple aquariums
- Water value documentation with graphs and tables
- Animal administration with notes and pictures
- Recurrent memory for care tasks
- Salt quantity estimation
- Nutrient and chemical adjustment calculators
- Extensive setting options

## Pricing and in-app purchases

Base price: Free.

**Subscriptions**

| Subscription | Price | Period |
| --- | --- | --- |
| AquaCalculator yearly | $19.99 | per year |
| AquaCalculator monthly | $3.99 | per month |

**One-time purchases**

| Purchase | Price | Type |
| --- | --- | --- |
| A large coffee | $3.99 | one-time |
| Something to learn | $39.99 | one-time |
| Ice Tead and a Sandwich | $9.99 | one-time |


## Recent user reviews (9 of 9)

All indexed reviews: https://appshunter.io/ios/app/aquacalculator/id1449511522/reviews.md

### 1/5 — Pricy for not much

*2024-04-17*

I like supporting apps but this is just a little bit overboard.  Too many apps want too much cash.  Asking a small yearly fee is fine 5 bucks maybe but otherwise…it isn’t worth it.  Good luck

### 1/5 — Not usable

*2023-07-16, version 2023.6.23*

All the app does is display a series of panels advertising what the app does. You can’t exit that advertising. The app is not usable.

### 5/5 — Great app

*2023-03-03*

Amazing

### 2/5 — Nice app great features poor execution

*2022-01-15, version 2022.6.4*

It’s clearly not an English app as not all strings have been localised. The UX is convoluted and confusing. To add a tank for example there is no onboarding instead you need visit “Master data” and add the tank and then in the main interface you can to work out how to select it. I feel the developers are clearly very smart as the functionality and science is clearly good but the app is very hard to use and understand.  It’s also very buggy, I ended up on screens with no way to cancel or get out, had one screen where the navigation title overlapped the cancel button so again I couldn’t get out. The tap areas for some of the input parameters are tiny. I feel that with a decent understanding of HIG and more use friendly UI this would be a top class app for marine aquarists.

### 1/5 — Paid

*2021-11-16*

$14 for a notepad?

**Developer response:** I am sorry that you are not happy or not in need of the featureset of the AquaCalculator. But AquaCalculator is way way more than a notepad. Please refer to the Apps decryption or our website to get an overview of what AquaCalculator has to offer to ease you day to day routine as an aquarist.

### 5/5 — Best app for dosing and water management

*2021-07-03, version 2021.6.13*

This is must have app for any reef tank enthusiast
It take the pain out of dosing 

I’ve tried other apps and no where as good as this i personally wouldn’t be without this app 

And would like to thank developers for making this app  

Trust me if you dosing your reef tank give this app ago it worth it and removes the hassle of getting dosing correct 

My tanks never looked so good

### 1/5 — Poor

*2021-05-16, version 2021.6.10*

Purchased the annual subscription and the app won’t work

### 3/5 — Closing app when click on Adaption for Ca

*2020-08-23, version 2020.6.25*

Just got the app today and when clicking on Adaptions for Ca option the app just close itself, tried restarting phone and app but still doesn’t work.

### 3/5 — 60% English - 40% German

*2020-01-17, version 4.1.9*

I’d love to give a 4.5/5 Star, unfortunately i can’t until the app is completely in english. Can use it for simple data entries, wouldn’t mind exploring the full potential of the application. However, it’s a great app full of potential! Please make it full english! 🙂

## Frequently asked questions about AquaCalculator

### What is AquaCalculator?

AquaCalculator is a reference software designed for dedicated marine and freshwater aquarists. It helps users document and manage all important parameters related to their aquarium's care, including water values, animal stock, and chemical adjustments.

### How does AquaCalculator's subscription work?

AquaCalculator offers a two-week free trial period. After the trial, a paid subscription is required for permanent use. Subscriptions can be stopped at any time before they become chargeable. Monthly and yearly plans are available.

### What are the subscription costs for AquaCalculator?

AquaCalculator offers a monthly subscription for $3.99 with a 3-day free trial, and a yearly subscription for $19.99 with a 14-day free trial. These prices enable full access and regular updates.

### Can AquaCalculator be used for freshwater aquariums?

Yes, while the main focus is on saltwater aquariums, freshwater pools can also be documented and managed effectively using AquaCalculator.

### Does AquaCalculator have ads?

No, AquaCalculator does not contain advertisements. The app is ad-free, allowing for an uninterrupted user experience focused on aquarium management.

### What kind of calculations can AquaCalculator perform?

AquaCalculator can perform realistic estimations for required salt quantities from various commercial sea salt mixtures. It also calculates exact dosing quantities for adjusting calcium, alkalinity (KH), and magnesium using low-cost salts.

### What devices does AquaCalculator support?

AquaCalculator is supported on Mac, iPhone, iPad, and Apple's reality devices, providing a versatile platform for aquarists to manage their tanks.

### How often is AquaCalculator updated?

AquaCalculator was last updated on June 16, 2026, with version 2026.6.8. Subscribers benefit from regular updates and enhancements to the software.

## Version history (last 5 releases)

### 2026.6.8 — 2026-06-16

Water parameter configurations are now synchronised via aCloud.

### 2026.6.7 — 2026-04-14

Bugfixes

### 2026.6.3 — 2026-01-22

Selection of animals from aPedia revised.
Fix: Subscription handling in special cases.

### 2026.6.1 — 2026-01-11

Some Bugfixes.

### 2025.6.5 — 2025-11-24

Bugfixes

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## More apps by Michel Mohrmann

- [MyTankLight](https://appshunter.io/ios/app/mytanklight/id544488591)
- [MW-Shops](https://appshunter.io/ios/app/mw-shops/id556526798)
- [Upside Down Text](https://appshunter.io/ios/app/upside-down-text/id1173186593)
- [Upside Down Text Lite](https://appshunter.io/ios/app/upside-down-text-lite/id1175053503)
- [GPSFix für Fotos](https://appshunter.io/ios/app/gpsfix-fur-fotos/id1474464432)

All apps by Michel Mohrmann: https://appshunter.io/developer/544488594

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*Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-07-07.*