Every article in the news that deals with hydroponics, beyond the latest marijuana grower bust, states that hydroponics is the practice of growing plants without soil using water and nutrients. It would be difficult to become even remotely interested in this form of indoor gardening to be surprised over needing them. Understanding what they are and how to use them properly will take some investigation and study.
Like all living things, a proper diet results in the best strength and vigor from your crop. As the grower, it is up to you to maintain the nutrition your plants need at various stages of growth. There’s more to it than just adding some solution to your water too. Exactly what you need to add and how much starts with your water, includes the current crop’s needs and must be measured for accuracy regularly.
Here’s a great video that will help you start to understand hydroponic nutrients.
If you don't find her at the desk - check the gardens. When not writing and weeding, she enjoys a good book, painting junk furniture, and blending the harvest of heirloom tomatoes and chiles into salsas.