Ahh nice.
I was expecting far worse. Those plants look reasonably healthy, just a little droop I can see in the background, but otherwise nice.
Sounds like you actually have this under control already, decreasing flow and raising pH. I try to keep my hydro pH between 5.8-6.0. Remember though that I'm a total noob too when it comes to playing in the water, lol!
Last Q, you don't have to answer, are you using RO or tap for source water, and are you adding CalMag? If you are using RO you really need to.