PH rise in DWC

As tap water sits, the pH can rise depending on what minerals/pollutants in your tap water. Use a filter to remove most of these nasty things, or use distilled water from any convenience store.

I had the Same problems when i started hydro.. dont use tap water. Or if you do, buy an RO filter for aquariums it costs only 50-60€ and then u got 0ppm either that or rainwater is fine. The PH swings are from all nasty sht in the water and no matter how much ph down you use it will keep rising and even become nasty cloudy and your roots will rot

just add water to balance.