The reason to use the Chlorhex in 30 days is because it tends to starts crystallizing out. This makes the rest of the solution too low to be effective. Truthfully, it sometimes crystallizes even sooner. If you use the Chlorhex, make up just what you need. Be sure to do a quick clean with it first to clear the surface, then recover it and allow the Chlorhex to soak on things for 10 minutes before wiping it off again.