Question about Lelit Filter 70L

That would be the idea. The water becomes softer and limescale no longer forms in the machine.

You shouldn't rinse a portafilter with descaling agent anyway (it depends on the type: certainly with a dual boiler like the Lelit Bianca). Instead, you should disassemble the machine, replace the seals and descale the boiler directly.

If you use a filter like this, you will only need a major service like this after a few years, when the seals start to leak...