Ok another thing to share.
In our first test we used the device in an aquarium where the stones not raise the water hardness (Fossilized wood)
The second test is happening in a Seiryu packed aquarium where almost 40-50kg stones are there.
Earlier i worried that the gas errode the stones. That is not happening on the other stones so maybe the one which has a light white patch now had an issue originally.
But! The calcium stuck in the diffuser plate in patches. Not sure of this will close down the mesh fully, but this is there in small patches.
I had contacted with Twinstar and they mentioned that they already fixed the issue and the new devices will hit Europe around this time.
But the old model has this issue with the mesh plate.
Twinstar also mentioned that the Calcium covered diffusers can be cleaned with a cleaning solution.
So if you face with this issue it's possible to clean. They told me too, that i can leave the unit in our Seiryu scape as it is possible to clean.
On our unit i do not see problems with the diffusion yet, but as it gets clogged maybe you will realize this on the performance.
Anyway it's good to know. Keep in mind guys. The new unit will come to europe shortly.
ps: Twinstar working nicely in our Seiryu scape. I try to share the images next week sometime.
But as i thought depend on your setup (crowded tank, high builds, flow) the unit helps you quicker or slower.