Recommended Boiler Cleaner?

[Ravenwoods]

I've just built manifolds for my home heating system (12 years old) and made major changes. So I am planning on using a boiler cleaner to flush out flux etc and sludge that may have accumulated in the system. I've heard of Fernox, and found Hercules at the Home Depot Website. Also found Sentinel X300 online. Anyway, just wondering what people recommend as being effective and cost effective.