The balance between Ca and Mg in your tap water is good.
To supplement I would use a complete GH booster, or else make your own with the right blend of Ca and Mg to maintain a ratio somewhere in the neighborhood of 4:1 Ca:Mg.
The most common GH boosters also contain potassium (usually K2SO4) and this is a good fertilizer, too. But if you are already dosing a lot of potassium some other way you might want to make your own GH booster.
I am using Niloq GH booster which is composed of magnesium:calcium:potassium 1:3:3
When using zorfox's calculator and set it at the estimative index method with a 2ppm raise I get these readings:
My tap water average reading for calcium is 53ppm and the average for magnesium is 14ppm.
As you mentioned most likely I already have enough of calcium and magnesium and there's no need to dose more. However, take a look at this picture:
Doesn't that appear to be a magnesium deficiency?
If it is, will the addition of my above dose of GH booster be enough to fix the issue.
Will the extra calcium make things worse? Will adding only 2.16 ppm of Mg be enough?
Since the above dose gives me 20ppm of K will that take care of K for the whole week or should I be adding more K when dosing Macros?
Or should I stop using GH booster and add Epsom salt to increase my magnesium levels instead.
By how many ppm should it be increased? Is the correct option MgSO4.7H2O?
Millions thanks for the replies