erkal I remineralise with tap water, check your alkalinity as Ca CO3 with your water supplier, or measure with a KH/Alkalinity drop kit (recommended). Then cut your Zerowater with tap water.
E.g. if your tap water is 160mg/L Alkalinity, mix 3 parts Zerowater with 1 part tap water to get 40mg/L alkalinity. You can do this in moments with a jug/kettle on scales.
40mg/L alkalinity is at the lower end of ideal, 60mg/L would typically be your max, but it’s easy to hit the lower side reliably.
Third wave water minerals can take a fair while to dissolve in DI water.