Can i reuse my water in DWC and in others hydro methods?

[Foreigner]

@Esrgood4u

then add nutrients to raise the ppm

I’m not a hydro guy so I don’t know how this works.

Do you do a math guess? I need to top up 5g in a 30g Rez so I need pH X and ppm X to balance it out?

Curious how this is done.