Maintenance

see

http://www.corrview.com/tech_c_15.htm

and other googled resources.... "The best way" to prevent depends on the size of the system, size of your pocketbook, and other critical factors.

(?)...in a "dry" piping system...? Are you certain it's MIC? Which type of organism?

Have you also investigated on the quality or maybe the origin or manufacturer of the piping to have a more direct answer, because same with my case, it depends on the manufacturer which they shortchange or alter their quality just to earn more profit.