I have used a similar 30khz zapper http://www.ebay.com/itm/Worlds-Smallest-Hulda-Clark-Zapper-30kHz-/350585983058
and have found it effective in reducing candida in the body. Notice I said reduce because you will not cure a candida overgrowth unless you radically shift your diet to foods that don't feed candida. I like to enjoy things like pasta, pizza, rice, bread, baked goods etc. All those will flare up my candida if I overindulge. So really it's an internal battle and the zapper is a good tool for that battle. I have also found that olive leaf extract and Colloidal Silver are very effective in reducing candida. If you tend to indulge in the candida feeding foods like I do you will have to basically stay on some sort of anti-candida protocol to keep it at bay. My2c

Steve