I think he means you fill your tank from the hot tap, thru normal resin.
if your tds is that high 4040 is prob best way to go. fast water production, relatively low wasteage compared to some, should be less than 10tds before resin. maybe as low as 2! but need good pressure, otherwise need booster pump.
try June at gaps water on 01706521074, she's fantastic, on same levels as Gardiners for customer and after sales service (I've found).