Hi,
As far as I can tell GH Booster has the following ingredients:
Calcium Sulfate
Magnesium Sulfate
Potassium Sulfate
Iron Sulfate

Since none of these are carbonates there should not be any effect on (carbonate hardness) alkalinity. This makes sense since it's called GH booster and not KH booster.

According to the Seachem website Equilibrium contains the following:
Potassium Sulfate
Calcium Sulfate
Magnesium Sulfate
Ferric (Iron) Sulfate
Manganese Sulfate

It's not clear if the compound ratios are the same but really it doesn't matter that much. You just need to add a bit of the booster to raise the GH enough to avoid deficiencies. I believe the suggested amount for GH booster is 1/8 teaspoon per 100 liter once a week.

Cheers,