ph issue

Hello, how is everyone.
this is my first grow indoor and im using biobizz try-pack its has bio-grow, bio-bloom, and topmax
the issues is with the Ph when i water without nutrients i try to lower the ph to 5.8 but when i water it and i check the ph of the water that came from under the plants it 7.4.

try to use a bucket 10l fill it at ph it to 6.5 for soil and 5.8 for hydro
I use a 10l bucket place ph meter in it reads 7.8 use ph down to 6.5 wait a hour then retest yo will notice the ph has changed again add more ph down till you hit 6.5 for soil or 5.8 for hydro lots don't do this but after a few hours you retest with ph meter if it reads 6.5 your ok retest again later on and if 6.5 you good to go it needs time to stabilize the ph in the water I have done this for years with no problems my ph run off is always around 6.2 some will say I'm wrong but that's them everyone has there own ways and differ to others so don't even ph at all with soil and even some say why test your run off so everyone if different