I don't run a big reservoir so I make 5 gals at a time. (gotta haul to 2nd flr.) Silica first, then I always mix A & C together at the same time in the same 5 gal bucket. After mixing well by hand and by small pump I add B and fully dissolve and then whatever else you're using.
I do use hot water in winter when its coming out barely 60* lol.
My pH with Jack's never moves ,my starting RO is about 10 ppm. If I blend with our nasty tap water I get pH drift upwards. The full mix with RO water finishes about 5.4ish and I have to pH up to 5.8. Kinda wish I had a slow drift at times from 5.6 up to 6.1 so we catch as many nutes as possible along the way
Is there something else in your add ins that could interfere. I do find I get precipitate if I don't take time and mix things right and even more so in colder months if I don't allow ample time.
Hope you get it sorted man.