I've basically confirmed that my overall plumbing problems are down to hard water buildup. My softener has been out of action for about a month or two (waiting on a part), so I have at least that much buildup to contend with. In case anybody cares, I have concluded this because major blockage issues began around the time the softener died, and because around that time efficiency of my water heater dropped drastically as well..
I'm told that a strong white vinegar solution is the best option, however my sources say that this needs to be followed up with heavy-duty mechanical cleaning, up to and including breaking down the plumbing system and mechanically cleaning the pipes individually. The intermediate plastic system eventually connects to an ancient metal system, so while I can conceivably do this for the plastic there's no way that I'm pulling metal pipes out of a concrete floor.
Is white vinegar really the best option? If not, what is?
Does it really require the mechanical cleaning I described?