Platinum Floor Coatings recommends cleaning your epoxy coated concrete flooring on a regular basis.  Loose dirt, dust, and other debris can be removed by regular sweeping and/or vacuuming of the surface.  

All spills should be cleaned up immediately to prevent chemical attack and staining of the topcoat sealer.

General cleaning of stubborn surface debris can be accomplished
using a mild, environmentally safe soap solution in accordance
with the manufacturer's instructions.  Harsh detergents, acids,
and alkali are not recommended as they can damage the surface.
We also recommend using a cleaner called Simple Green.  It works
very well on cleaning stubborn messes and won't harm the epoxy.  
Hard water stains can be cleaned with a solution of 1 part by volume
white vinegar with 3-5 parts by volume water.  

How to clean epoxy floors
Clean Epoxy Floors