Scott Dekarske of Wet-Werk Hydroponics in Memphis, TN shows how to change the nutrient solution in a hydroponics/aeroponics system.
To see how to built this hydroponics system: https://www.youtube.com/watch?v=_ewOsgoGQL4.
To change the nutrients: first Scott unplugs the pump and drains the water from the tub. Once the water is drained he checks the roots to makes sure all is well. Then, he measures out the new nutrient solutions in individual measuring cups. He is using a three-part nutrient solution. He takes a pH sample of the water he will be putting into the system. It is in an acceptable range so he does not adjust the pH. Then, he carefully divides the measured solution between the two buckets holding the water. Between adding each nutrient he mixes well. When they are all mixed up he pours each bucket into the tub, turns on the pump, and checks to make sure the sprayers are all functioning properly.
For more interesting ways to grow your garden watch these videos:
Hydroponics Basics: https://www.youtube.com/watch?
Planting an Herb and Flower Container Garden: https://www.youtube.com/watch?v=8rmH5LsKvBk&t=1s
Building a Hoop House: https://www.youtube.com/watch?v=6NmOLcSrats