I already purified them with sage after I finished the grid. But you can purify them again if you want.
You can use holy wood or sage to purify. If you don’t have these two things with you, you can meditate and use pure white light to purify them.
Here I will teach you how to use pure white light to clean. When you enter a meditative state, please imagine your crystal grid. Imagine there are some negative things coming out from the crystal and let these negative things go into white light. Then you can imagine the pure white light going into your crystal grid with love and happiness.
Next step I will teach you how to set up your crystal grid. You need to prepare a paper and pen. Writing down the details you want the crystal to help you, not anything but need to be related with the grid you bought. Fold the paper and place the paper behind the crystal grid. Now, you need to use your imagination. Imagine the paper carrying your wish goes into the crystal grid and permeates together. Great! you finished the setting!
The only thing you need to do is let the crystal grid keep clean. And if you want to reset them, you need to purify them and repeat the setup step.