In each type of hard water analysis that each type of water source is different and will have different softener. If the water is very hard to use EDTA. Best water softener that EDTA is used less or more.
In the analysis of each type water softener The water sources, each with different and will have different hardness. If the water is very hard to take much EDTA. The water is a little hard to take less EDTA.
In the analysis of each kind of water hardness The water each type has different sources and have different hardness If the water hardness is used EDTA. The water with low hardness is used EDTA less.