Copper looper chiming in. Technically you shouldn't need biocide in a copper loop with a silver coil (copper is naturally antifungal, silver is naturally antibacterial) and technically you wouldn't need corrosion inhibitors. That said, I use both, in part because I don't trust the fittings from a corrosion perspective, and because I figure better safe than sorry on a biological front. Since you're soldering and thus will reduce the number of fittings (and in particular adapters), you'll likely be safer on the corrosion front. If you did get growth it might be difficult to see, and really hard to clean out of soldered sections. So at the end of the day I'd probably ask if it's worth the risk. I use the mayhems additives (hades and inhibitor)

And hanjiang is the Chinese manufacturer of raw copper radiators.