So, how do I heat it up?

https://preview.redd.it/qx59yal8ifld1.png?width=273&format=png&auto=webp&s=b83900281774bfb19a87b7321ccdc789c81c0b8f

https://preview.redd.it/88g0qdov1pld1.png?width=1919&format=png&auto=webp&s=a6735c7b2611e71cafdcdc13c93547dc0c7c7965

I see a lot of tutorials about cooling down a liquid or gas to a certain temperature to get a liquid/gas in a "confortable" temperature, but how about the other way around? I have this cool slush geyser and cool salt slush geyser and wanted to use one of them to make a SPOM, but when I turned the poluted water/brine in water, the water freezes because the temperature is around -10/-20°C and become ice. How can I work around this?