You need to mix new Chlorhex every time you use it. Also keep in mind that you'll want to scrub water bowls before soaking them to make sure there's no organic matter on them before they go into the Chlorhex, as prolonged exposure to organic material weakens its effectiveness.

I personally prefer Virkon S & Trifectant. Expensive, but it's the disinfectant version of "nuke 'em till they glow, then shoot 'em in the dark" when it comes to many, many viruses & bacteria. It's also good for 7 days once mixed, and if you're thorough & efficient in your cleaning techniques, a little can go a long way.

Regardless of what you use to disinfect, you must thoroughly clean beforehand. Disinfectants don't cancel out the need for cleansing & scrubbing & removing funk from whatever it is you're trying to clean/disinfect.

HTH!

K~