When WD spoke about it, he didn't say SCRUB IT CLEAN!!! it was just... be careful and do a 100% water change, traces of it will remain but they will not harm the fish and over time will go. I almost put the filter back in without cleaning the top of it which had bicarb over it...whoops

I gave the inside a clean and scrubbed it down only like I would normally... I think thats more than enough tbh.
I want my pH to be like 6-6.5 but doubt it will happen
You should stop talking to people at your LFS

100% water changes had no notible effect whenever I've done them... I don't know how you could even work in a fish shop and not know that!