EnforceOurConstitution

A trove of good comments, thank you all! Chem Geek mentioned Zeolite4A. I found it in an inexpensive pellet form on Amazon that can be heated and reused. I'm a newbie so may be missing something but it seems like an affordable option for a hot tub: Molecular Sieve Zeolite 4A 8X12m 300g https://www.amazon.com/gp/product/B01MDSU1KT/ref=ox_sc_act_title_1?ie=UTF8&psc=1&smid=A1MWRZVF3AZEJX 4A molecular sieves are the sodium form of aluminosilicate zeolite A. Their structure forms a network of pores approximately 4 angstroms in diameter, through which only very small molecules such as water, methanol and hydrocarbons up to propylene can pass. This makes them useful for removing water from mixtures with larger molecules. They can absorb up to 20% of their weight of water, depending on the surrounding water concentration and other conditions. They can be dried for reuse by heating at 200-300C (400-600F).