I have a Jandy 400K Btu heater but the heater manifold was bad and so it's leaking and not working. The PB has the part ordered but it's currently on back-order so they'll come tomorrow to bypass the heater for now until they can replace the manifold. I asked a while back if they can just replace my heater since it's brand new but they said even those were back-ordered.
List ALL of your equipment in your signature with model numbers. Knowing all your equipment is more important then the length of your stone.
Low pH can damage the heat exchanger. How do you know he pH was 6.8 and not lower? I would put your PB on notice in writing as to what his guy did should the heat exchanger fail prematurely. This is where they will do things that will come back to haunt you later. You should not let them add any more MA without your supervision.
As for hanging the sock, I have an A&A in-floor cleaning system and unfortunately no returns, just the pop-up heads (which are working great, of course it's brand new so we'll see for how long). Without returns, what can I do? I just saw a YouTube video and the guy hangs the sock in the skimmer, ties it to the skimmer cover and leaves it dangling there. Is this something I can do? It's a Venturi style skimmer but I assume it would work the same for this purpose, right?
Skimmer will be ok. Make sure the sock cannot get sucked into the skimmer pipe or block it. Run your pump 24/7 while the sock is in the skimmer.