Watercat Cube - Descaling system recommendation / experiences?

So, what exactly was unserious about it again?

Where should I start? The associated website? The quality of its translation? The imprint? The "Fulfillment Center" in Dublin? The "processing" in Kent? The customer service in Kolin? The missing DIN-DVGW certificate? The legal requirements of AVBWasserV? The requirements of DIN 1988? The requirements of DIN EN 806? Product liability law? Manufacturer conformity declaration? Which contractual installation company of your drinking water network operator installed and maintains the system according to the valid rules of technology? The list can go on indefinitely. But stinginess is just cool, especially here in Germany, when it comes to our basic foodstuffs.

Calm down, calm down, you have to watch your blood pressure. You can research your questions yourself. I certainly won't name the installation company here. But don't worry, everything is professionally installed and regularly inspected and maintained. Some people just have something against a product that can do and does the same and is even cheaper. Look at it this way, if this thing blows up our place, then that's not your problem and I will honestly tell you: you were right!

So even the missing DIN-DVGW certificate would be a no-go for me... Sorry, that thing just won't do.

So the missing DIN-DVGW certificate would be a no-go for me... Sorry, that thing just doesn't work.

The DVGW is anyway questionable. The thing works, even very well, for 7 years. CE marking as well as NSF, ISO, TÜV, FDA and several other quality certifications are available for those who absolutely need them

Sorry, DVGW is not open for discussion for me... When it comes to drinking water, the fun stops for me, but to each their own.

The DVGW is questionable anyway.

The DVGW is the industry association for the gas and water industry here in Germany. Its main task as such is the creation of technical regulations that ensure the safety and reliability of gas and water supply. Through this technical self-regulation of the industry, recognized rules of technology arise, which are referred to in legislation; these rules have the character of law in terms of liability law issues and in cases of damage.
If, according to your individual, personal opinion, the DVGW is "questionable," that already shows quite well what kind of mindset one is dealing with.

...regularly inspected...

Inspections can be carried out exclusively by state-recognized experts, just by the way.

Some just don’t like it when a product can do the same and also be cheaper.

As already said, being stingy is cool. I’m happy for you that you and yours managed to snag such a super cheap ultrabargain and that the thing works for you. However, at the next drinking water network contamination, I don’t want to be in your shoes. Then drinking water network operators increasingly tend to look for someone to blame. And usually, those are the ones who install without VIU devices without certification. But everyone has to decide that for themselves. Better to save a few hundred on the device and then have 2-3 times the operating costs.