After riders just rinse through. Then hang it up and let the air get to it, take mouth pieces apart and store in draw. Store same way, hanging up. The air will keep it nice and bug free. Every 6 months or so I use a milton cleaning tablet and give it a good cleaning. Cheap as chips.
I do use the sugary electrolyte drinks etc
If you store it wet it will go black. Its the moisture that promotes the growth.