How to maintain a Saniflo waste water macerator pump?
White Vinegar, as in regular household, kitchen variety. Vinegar will do the job without harming rubber seals.  It will easily descale most lime build ups.  You should likely mix with plain water in a 25x75 mix, depending on how much you intend to use.  For mine, I use just enough total mix to completely cover the base of the pump base. up above the grinding blade, so, roughly 2 gallons total mixture with 1/2 gal US or 1.5 liters metric of vinegar with 3 times more of water.... so 1/2gal vinegar, 1.5 gallons of water, is enough for the fluid level to be above the actual grinding blade in my particular pump.  I let that stand for at least an hour, then flush the whole system with clear water.

The advantage to vinegar is that while it is acidic, it is not enough to kill off the useful bacteria in the entire waste system nor is it so strong as to damage plastic or rubber seals.