Since you're mixing Ca and Mg into the solutions ignore the ratios of the GH boosters. All you're are looking for is adequate Ca and Mg. Plants are going to use 1-2ppm per week maximum. So dosing 4ppm/week will provide more than is needed and not impact other things.
You cannot use CaSO4.1/2H2O in a solution due to the solubility. The maximum solubility is 2.1mg/ml. Instead use Ca(NO3)2.4H2O (Calcium Nitrate Tetrahydrate). The solubility is better and it will also provide NO3.
Below is a recipe for your tank which will provide Ca and Mg in adequate quantities. Don't forget the trace mix
The container size is 500ml and each dose is 41.6ml (enough for 4 weeks at 3 times a week dosing).
One dose will supply the following levels.
NO3 7.5 ppm
N 0.763 ppm
PO4 1.3 ppm
P 0.424 ppm
K 7.5 ppm
Ca 1.333 ppm
Mg 1.333 ppm
S 3.523 ppm
Add these to your 500ml container.
(x1) Ca(NO3)2.4H2O 17.868 gm (approximately 1 1/2 teaspoons)
(x1) MgSO4.7H2O 30.751 gm (approximately 6 1/32 teaspoons)
(x1) K2HPO4 5.424 gm (approximately 1 teaspoons)
(x1) KNO3 12.523 gm (approximately 2 1/2 teaspoons)
(x1) K2SO4 21.804 gm (approximately 3 1/2 teaspoons)
The levels above are for a 50 gallon tank using a container size of 500 ml and a dose size of 41.6 ml.