The hardy stoves use a lot of water, that's why they have an automatic filling system because they lose a lot of water. I've seen folks have that part unhooked or see it fail and add a couple gallons a day. That being said, pour all the chems you want in it, it will be gone n a month.
As far as the pump, maybe there is a reason behind the cast iron and the 304 debate, not sure, there are no specific regulations with empyre on there 304 stainless stoves however, that being said the empyre 304 is well over twice as thick as the hardy. Not sure why there dead set on the bronze pump, but I would like to learn more about it