No you don't! The pool shop is used to testing CHLORINE to be the main sanitiser in pool water.
Cyanuric Acid (Stabiliser) is used to hold and trap chlorine in the pool. This is not required with the Naked System and why we state, although we produce chlorine, without stabiliser, you're not swimming in chlorine.
You can find out more of the differences about the Naked System compared to chlorine/mineral based systems from the following links: