The plants' water hardness requirement is only stated if
the hardness has an important effect on growth.
It is most often the water hardness in
connection with the pH value which is of importance. A
coming page on water chemistry will contain more
information about this.
||(GH <3 dh)
||(GH = 4-8 dH)
||(GH = 9-13 dH)
||(GH = 14 - 20 dH)
||(GH > 20)