Question about Lelit Filter 70L

Apparently BWT Bestcup has a solution with a standard adapter that should fit the Lelit. The standard Lelit filter is too expensive for me, but I haven't tried an alternative yet. That's why this is only "research" and not "tried out".
As far as I have seen, there are also refillable filter cartridges where you can replace the granulate yourself. That would be almost the most attractive option for me, but I haven't seen a suitable filter cartridge yet - except for the brand Eigenbau.

Galaxus does not have the item available, but that is no reason to look for another suitable filter. Have a look at the Lelit importer messinacoffeestore.ch