I'd recommend decanting the liquid off the top and then adding previously boiled water to the jar (COOLED FIRST!
) Then swirl everything up and let it sit for 30-60 minutes. You will see a darkish-grey band around the bottom. Decant and save the liquid off the top as this will be most of your good, healthy yeast. Get it even cleaner by letting it sit again. Otherwise seal it up, label it, and throw it in your fridge.