CaOH can be added to water that continues to foam. It's well known that calcium deficiency can lead to foaming in spas. Keep in mind that you don't want to add anything containing carbon such as chalk (CaC03). I had some interesting foaming issues that not even simethicone could help for longer than an hour or so. So, I did some reading and decided to try some food grade pickling lime (a.k.a. slaked lime) and all foaming issues are gone. Give it a try and you're welcome!