Ppm for a ratio of K10:Ca20:Mg5:

Ca = 34, GH = 6.56:

Element	ppm	GH
K	10
Ca	34	4.76
Mg	8	1.8

Ca = 20, GH = 3.94:

Element	ppm	GH
K	10
Ca	20	2.8
Mg	5	1.14

Mixing the GH =3.94 solution
in a 5 gallon volume (19 liters):

Chemical	grams	ppm	KH/GH	Notes
K2CO3	0.35	10.4 ppm	KH= 0.75
(or K2SO4 )	0.42	9.9 ppm	KH=0	+ 12.2 ppm SO4
CaCl2	1.00	19 ppm	GH = 2.66
MgSO4.7H20	1.00	5.19 ppm	GH = 1.19	+ 20.5 ppm SO4

Reconstitution mix to get K10:Ca20:Mg5
and Total GH/KH = 3.85/0.75:

Chemical	grams	ppm	KH/GH	Notes
K2CO3	0.35	10.4	KH = 0.75
CaCl2 (anhydrous)	1.00	19	GH = 2.66
MgSO4.7H20	1.00	5.19	Gh = 1.19	+ 20.5 ppm SO4