wrote...
...
The process involves ... a submersible pump, ...
The pump is usually trashed after pumping phosphoric
for a couple of hours (but maybe not... had a little
all-plastic thingee that didn't seem to mind the
chemicals at all).


"Little Giant" brand pumps. They make hundreds of models. The
hardware stores carry the ones for water pumping (pool covers,
fountains, etc). Low cost, high quality. They also make a bunch for
chemical pumping at similar pricing. Used to order them on occasion
for customers back when I sold hardware.

Daniel