The individual dip method is probably a waste of time and effort 99% of the time. There is no way of knowing if you are getting them all, including all of the different stages of life they are in. I tried that with my tricolor valida and thought it worked. A week later they were all back. The only things in my tank that I killed were my pods and my cleaner shrimp (the ******* wouldn't let me catch him). My hermits even survived. Maybe they locked their shells and didn't come out 'till it ws over.