Z21 vs EHEIM Digital Connect
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
Z21
Control your model train layout and locomotives wirelessly from your iOS device. Manage your locomotive library, program digital components, and operate switches and signals with an intuitive touch interface. Enjoy a realistic train control experience with customizable driver cabs.
- Wireless control of locomotives and layout
- Manage locomotive library with images
- Program digital components
- Intuitive graphic interface for switches and signals
- Downloadable driver cabs for realistic control
- Demo mode available
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Use this app to connect to a Z21 Digital Center. A demo mode is available. With this app you can manage locomotive libraries, locomotives and locomotive functions, program digital components – and of course control all locomotives with DCC- or Motorola-decoder, as easy and convenient as is only possible with touch-technology. The digital switchboard Z21 connects your model train unit and your digital locomotives with your iOS device via WLAN. This way you can control the operation on your train layout easily and conveniently from your mobile device. Model train control was never this easy and convenient: With one swipe of your hand you can scroll to your model of choice in the locomotive library. A slight touch on the headlight symbol and the front and backlights go on. A second touch, this time on the speaker symbol, and the locomotive makes a sound. Drag your finger over the speed indicator and the train accelerates. The further highlights of the Z21-App • Control your entire layout with an intuitive, graphic interface and have easy access to the entire scope of functions of your digital locomotives. • Manage your entire locomotive-library in just one application, including individual locomotive images for an ideal overview. • Control the digital functions of your locomotives with intuitive function symbols instead of complicated key combinations. • Create a blueprint of your railway system and control your switches, signals and modules with a single click. • Download driver cabs and control your locomotives from a real train driver’s point of view.
EHEIM Digital Connect
This app allows you to connect, set up, and manage various EHEIM digital aquarium devices from your smartphone or tablet. Customize settings for optimal results and ensure your devices are always up-to-date for a thriving aquatic environment.
- Connect and manage digital aquarium devices
- Customize device settings
- Update device firmware
- Control filters, lighting, heaters, and more
- Monitor aquarium components
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EHEIM Digital Connect App – Your Aquarium Smartly Connected Simplicity and Control at Your Fingertips The EHEIM Digital Connect App revolutionizes the way you manage your aquarium. With intuitive operation and a simple touch of a button, you can connect, set up, and manage your EHEIM Digital devices at a new level. Effortlessly update your devices to always benefit from the latest features. To ensure smooth communication and updates of the devices, it is strongly advised to ALWAYS set the latest device from the EHEIM digital family as the master. Customization for Optimal Results Tailor the settings of your EHEIM Digital devices to meet your personal needs. Whether it's external filters, LED lighting, aquarium heaters, pH control, feeders, climate control, or UV clarifiers – control and monitor all components conveniently from your smartphone or tablet. Intuitive Management for a Perfect Aquarium Experience an intuitive and efficient way to manage your aquarium. Keep track of your devices and improve the living conditions for your aquatic inhabitants. Compatibility and Future-Proofing The EHEIM Digital Connect App supports all current and future EHEIM Digital devices, ensuring that your investment is protected for the future. Supported Devices: - EHEIM Digital External Filters: EHEIM professionel 5e, EHEIM classicVARIO+e - EHEIM Digital Lighting Control: EHEIM RGBcontrol+e, EHEIM classicLEDcontrol+e, EHEIM LEDcontrol+e / EHEIM LEDcontrol+ - EHEIM LED Lighting: EHEIM classicLED daylight, EHEIM classicLED plants, EHEIM powerLED+ fresh plants, EHEIM powerLED+ fresh daylight, EHEIM powerLED+ marine actinic, EHEIM powerLED+ marine hybrid, EHEIM powerRGB, EHEIM incpiria furniture lighting - EHEIM Digital Aquarium Heaters: EHEIM thermocontrol+e - EHEIM Digital Climate Control: EHEIM climacontrol+ - EHEIM Digital pH Control: EHEIM pHcontrol+e - EHEIM Digital Feeder: EHEIM autofeeder+ - EHEIM Digital UV Clarifier: EHEIM reeflexUV+e Download the EHEIM Digital Connect App and discover how easy and efficient managing your aquarium can be.
Screenshots
Verdict
The clearest difference is rating: Z21 at 3.8 against EHEIM Digital Connect's 1.7. Z21 also leads on review sentiment (38% vs 15%). EHEIM Digital Connect's advantage is in-app purchases (none vs 1). On price, ratings volume, update cadence and ads there is nothing between them.
Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS
Both are free to download. Z21 sells 1 one-off in-app purchase. EHEIM Digital Connect asks for nothing beyond the download.
Z21 holds the better App Store score, 3.8 against 1.7. Both are backed by a comparable volume of ratings — 13 and 12 respectively. Written reviews point the same way: 38% of Z21's written reviews are positive against 15% of EHEIM Digital Connect's.
Z21 ships an update every 3 weeks, EHEIM Digital Connect every 5 weeks. The most recent releases landed on October 6, 2026 and October 15, 2026 respectively.
| Parameter | Z21 | EHEIM Digital Connect |
|---|---|---|
| Price | Free | Free |
| Rating | 3.8 (13 ratings) — better | 1.7 (12 ratings) |
| Positive reviews | 38.3% of reviews — better | 14.8% of reviews |
| Number of ratings | 13 — better | 12 |
| Update frequency | Every 3 weeks — better | Every 5 weeks |
| Ads | No | No |
| In-app purchases | Yes | No — better |
| Monetization | Free with in-app purchases | Free — better |
| Devices | iPhone, iPad, iPod — better | iPhone, iPod |
| Requires iOS | 12.0 — better | 13.0 |
| Further details — not scored | ||
| Size | 232 MB | 47 MB |
| Age rating | 4+ | 4+ |
| Developer | Modelleisenbahn GmbH | Eheim GmbH & Co. KG |
Customer experience
Z21
EHEIM Digital Connect
Bugs and requests
Z21
Reported bugs
17 issues- App crashes on startup (white screen issue)
- Connection drops to Z21 central station
- Throttle display shows incorrect or blank speeds
- Function buttons not responding properly in multitraction mode
- Route synchronization failures across multiple control station pages
Show 12 moreShow fewer
- Weichen (turnout) display showing white/blank images
- App freezes during speed adjustment
- Export functionality crashes (PRO version)
- Occupancy feedback not displaying (Roco 10808)
- iOS 14+ compatibility issues
- Slow response times and lag
- Layout elements jumping off-screen when editing
- Routes highlighting incorrectly or not at all
- Password-protected bug report zip file inaccessible to users
- Fleischmann turntable module not available
- Bridge modules cannot be displayed diagonally
- Data loss after app updates
Requested features
20 requests- Offline locomotive database access
- Dark mode or customizable color schemes
- Background image support for layout design
- Turntable/rotary module support
- Automatic event-based control (occupancy detection, crossing automation)
Show 15 moreShow fewer
- Pendulum train control functionality
- Manual route deactivation capability
- Larger emergency stop button
- Locomotive database sharing between layouts
- Multi-language support (Spanish, French, Italian, Russian, Japanese)
- Diagonal bridge module display
- Camera locomotive integration
- Double slip switch operation
- Text labeling in layout designer
- Improved signal image selection interface
- Vehicle filtering and categorization system
- Windows/Mac desktop application
- Start-destination buttons for easier route control
- Occupancy feedback module support (Roco 10808)
- Copy and paste functionality in layout mode
EHEIM Digital Connect
Not enough reviews yet to summarise bugs or requests.
In-app purchases
Z21
- Z21 Full Version$17.99
EHEIM Digital Connect
No in-app purchases









