unstable pH of well water

I want to grow in coco (canna coco pro plus) and bought liquid pH test indicator.
I'm using local well water which has pH arround 6.5 when fresh
But if I keep that water resting for 6+ hours it changes PH somewhere to 8+

So I add nutrients to the water then adjust pH to optimal level and immediately after that start watering plants with solution that has right pH at that time.
Should it be okay? Or is it problem that my well water is not pH stable by default and changes after some time?

thanks

yes ,after you add all your nutrients and they are mixed well let it set for about 30 minutes and then PH up or dn ,water wells are crazy sometimes but i still prefer the water for my consumption .

you may want to go and get a water filter. the nutes should have ph stablizers which should make the ph problem a non factor but you should really be thinking about whats causing the fluctuation itself. it sound like you have a microb in the water

Micro-organisms can cause wild ph swings.

Usually algae.