Basics

The pH of your nutrient solution can greatly impact the growth of your plants. In general, you want to keep the nutrient solution between 5.5 and 6.5 (slightly acidic) for proper nutrient uptake. This stuff goes a long way.

Science

Nutrients are simply a mix of different elements and minerals. They dissolve into water at a certain pH range. Get the pH drastically wrong and your nutrients will precipitate out of the solution (think of sugar that won't dissolve in water) and be unavailable for the plants to use creating a relative nutrient deficiency.

Usage

Use per packaging. Fill indicator vial halfway with nutrient solution (we recommend testing the entire solution BEFORE mixing the nutrients as the nutrients cause a momentary change in pH for a few hours, but corrects itself as the powder dissolves) and add a few drops of indicator solution into the vial. Compare the resulting color of the solution. Add pH down if the pH is above the ideal range and pH up if the pH is below the range. Start with small amounts of pH up down until you get the hang of it!

Remember, you are working with acids and bases which are dangerous if they come in contact with skin/eyes/mouth. Use proper protection.