se cerchi su internet in qualche shop lo hanno...e li c'è scritto tutto per filo e per segno...è già da un po' che son in giro...sono progettati per vasche grandi e di conseguenza qui da noi non sono molto diffusi...hanno forme strane e sono molto ingombranti a mio modo di vedere...
ti riporto una descrizione di uno shop:

The DaStaCo calcium reactor is a fully automised system and is the most userfriendly system on the market today.
The de-aeration of the calcium reactor at regular intervals can be automised by means of an external digital time-clock of your own.

The DaStaCo calcium reactor is equiped with a central controller (Flow Control, incl CO2 control, alarm).

Our latest central controller provides the following three functions:
1) Flow Control
The flow control regulates a dosing pump for calcium reactors.
This provides the user to dose extremely precise and in a very stable way the necessary calcium and bi-carbonates to the aquarium to compensate the consumption within the aquarium.
You mesure the Kh value in your aquarium, if it is necessary to increase the Kh, just turn the flow control knob to the right.
If it is necessary to decrease the Kh, just turn the flow control knob to the left.
It can't be more easy than that.

2) CO2 control
This automatically regulates the supply of CO2 regarding the need in the DaStaCo calcium reactor, and the Co2 supply is adjusted automatically if the water flow increases / decreases.
Our central controller replaces thus a pH controller and pH probe, so you can forget the work to calibrate Ph-probe's at regular intervals.

3) Alarm monitor
The DaStaCo is the only reactor in the world that monitors if the Co2 bottle is empty, and need to be re-filled.
In that case, the CO2 solenoid valve is automatically closed, otherwise the solenoid valve will stay open forever like with other calcium reactors.
The user is informed of this through a notification LED + loud acoustic signal.
The DaStaCo is the only reactor in the world that monitors if the circulation pump fails or is jammed/blocked.
In this case also the Co2 solenoid valve is automatically closed.
The user is informed of this through a notification LED + loud acoustic signal.
The DaStaCo is the only reactor in the world that monitors whether there is somewhere a leak in the CO2 flow to the reactor.
In this case also the Co2 solenoid valve is automatically closed.
The user is informed of this through a notification LED + loud acoustic signal.


Additionally, you need the following equipment if you don't already have them.

- Dosing pump for calcium reactors (peristaltic pumps like our Oliver Joos dosing pump)
- Co2 bottle
- Co2 solenoid valve 220v
- CO2 check valve
- Double gauge Co2/pressure regulator with fine adjustment valve
- Reactor media

direi che non sono nulla di particolare.........tranne per l'efficenza e quello non lo metto in dubbio visto che non li conosco.
ma apportare kh o calcio in maniera non bilanciata.....direi che è chimicamente impossibile .

The DaStaCo calcium reactor produce kh and calcium in a balanced manner.