Is there anything I can pour into a water heater that will dissolve
mineral deposits and definitely not damage anything inside the tank?
Hopefuly something that will work in a somewhat diluted solution since
buying enough Lime-Away etc. to fill far enough to reach the lower
element obviously isn't practical.

The tank is installed in such a way that once drained it would be
simple to detach it and move it around so rinsing and draining several
times shouldn't be too much of a hassle.

Thanks for all input.