Is hard water acidic or alkaline?

[Noe]

I think if you want to lower the pH of your media, you need to prepare the fertilizer solution first and check the pH level. If OK, you don't need to add any acid whether apple cider vinegar or some of the other acids. But, if you need to add acid, do it gradually, perhaps a quarter teaspoon at a time, then check the pH until you reach the correct range. You need to do this only once or twice. After that, you should get the feel on the pH level of your watering.