I cleaned mine with vinegar.
I poured 6L of the cheapest vinegar, fill with few liters of water, left it for a while and then drained it through taps.
After that I rinsed with water, several times with a smaller amount.
Vinegar is good because dissolves limescale well, it cannot corrode metals (like all other organic acids), it is not poisonus and it is cheap. But next time I will use citric acid, the same positive qualities but does not smell like vinegar.
I will additionally do disinfection with Izosan G.