A weekly dose of Raritan C.P.
It's a bio-enzymatic cleaning product that destroys odor on contact and "eats" hair, body oils, soap scum, molds, fungi and algae (although that's not what's in your sump...algae can't grow without light) etc. A few oz down the shower drain will keep your sump clean, slime free and sweet smelling. An annual or semi-annual cleaning with detergent wouldn't hurt either...but do NOT use bleach, chlorine or any product containing chlorine...it's highly destructive to hoses and the rubber parts in the sump pump.Btw (before anyone asks)...C.P. would also work in a bilge, but you'd need a gallon a week in an area that large to do any good, making it way too expensive to use as a means having a clean odor-free bilge without doing any actual work.