pH Up is a highly concentrated liquid pH adjuster made by Advanced Nutrients, designed to raise the pH of your nutrient solution or growing medium when it’s too acidic (i.e., pH too low).
The active (or primary) ingredient is potassium hydroxide (also referred to in some specs as caustic potash) — so you’re dealing with a strong base.
It’s intended for use across various media: hydroponics, coco, soil, aeroponics, etc.