I see I wasted my time replying since you never bothered to answer the questions. So I probably wasting my time again, so I wont make it long or elaborate much.
1.) If your initial pH is actually that high you have HARD water, and a RO system that's not working correctly (probably clogged due to the hard water).
2.) Electric meters often give false results. I'm not sure what you mean by "and PH indicator solution," but unless your using pH drops to check pH, there's a chance your readings are not correct.
3.) When the water supply has high pH you ALWAYS adjust pH both before and after adding the
nutrients.
4.) Citrus acid (designed for hydroponics) works just fine as a pH adjuster. If you want something with more longevity (buffers), use GH dry pH adjusters. But never use anything like battery acid or Muriatic acid that is
NOT designed for hydroponics. And before you say Howard Resh said to use it again, I know who Howard Resh is and his credentials. You have a problem with your water supply and method in which you adjust pH, not a problem the pH adjusters. Sticking harsh chemicals in the water won't change that.
P.S.
You may very well have other issues going on other than your water supply and pH adjusting methods. But since you don't bother to answer any of my questions, I can't help you. You want to fix a problem, start with the basics to narrow down the problem. Putting a band-aid on it will cover it up, but won't make it go away.