The model I have only has two frequencies: 35kHz and 1kHz. I have been experimenting with both, but I feel more vibrations when I use the 1kHz, so I figured 1kHz might be more effective. Yeah, I'm figuring I put too much centralized zapping in one place at one time, so I was bound to have some reaction. Ionizing water sounds interesting. I think I should look into that. Thanks.