I'm not sure if my machine even has a hardness marking, but when I used liquid dishwasher soap, I simply filled up the compartment every time.
As to the cost, yes it's 3X, but if you're reading this and you have a Costco membership, it's still a rounding error.
Pods just make life simpler and cleaner (no messy powders and gunky liquids in the soap cabinet), which is why I even have a dishwasher in the first place.