Occasionally, a small amount of white fuzz will show up on your growing media. This is likely a beneficial fungi that grows naturally on both soil and hydroponic media. It is part of a healthy ecosystem where moisture and organic material are present. You do not have to worry about it negatively impacting you or your plants in any way.
As your plants grow, the fungi will disappear from view. But if you prefer, it is ok to remove it with your fingertip or a Q-tip. You can also add a drop of hydrogen peroxide to remove it.
Keep in mind that this white fuzz will not grow on your plants. There is a similar looking, but different fungi that grows on your plants. It is called Powdery Mildew. You will want to remove it so that your plants are as healthy as possible. Learn more about powdery mildew here.
Let's Grow Together!