Due to my current weakness in understanding water chemistry (which I am working on and experimenting with), I am having trouble determining just how closely the "Barr's GH Booster" and "Seachem Equilibrium" match chemically. Are they essentially interchangeable? Do they affect GH and Alkalinity the same?

I know this is a bit of a dumb and lazy question, but I am not sure if I am understanding my test results correctly or not, and I have just run out of Equilibrium and have a bag of GH Booster on hand!

Thank you very much.

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,

Would, for example, 1 tsp of GH Booster equate to 1 tsp of Equlibrium with respect to dH of GH?

As best I remember, Greg made the GH Booster so it was to be dosed the same as Equilibrium. As long as it is close to being the same there is no reason not to assume it is the same. You need a certain amount of calcium and magnesium in the water, but the exact amount is far from critical.