I'm working on getting my system setup, however, when I do get it setup, I think I'll do it like this.
6 months-Flush system with new water and additive
12 months-Either upgrade components or open components and clean, then flush system and replace tubing if clouded.
Those little spigots that you throw in-line in your system look like they work very well. Just attach that thing to it, when you need to empty the system you just turn the spigot a bit.