I run about 35 PPM CYA. It is enough to keep the chlorine from being burned off too much by the sun, but minimizes the negative side effects. Keeping it low leaves a little headroom in case the SWG fails right when we're going on vacation. The low CYA would allow us to run a tri-chlor floater for a while, if necessary, without driving us to have to do 25 PPM shock treatments.