Yes, people can have GERD symptoms with low acid levels, normal acid levels, and high acid levels because they are many different things that can cause GERD. I can get really bad GERD if I eat certain foods. Especially if it's foods with certain additives.
I cannot eat foods with MSG or certain amounts of sulfites. And dairy is out of the question for me, at least for now. I don't drink cow's milk anyway because it's not good for you, but cheese is a big weakness for me and it kills me that I can't eat it.
I tried eating some organic greek yogurt recently and at first it went down okay, but then I started getting these horrible pains in my stomach. I'm still not sure if the pain is coming from protein casein or the dairy causing extra acid production or the good bacteria killing off the bad bacteria (when bacteria die then can release toxins) or a combination of these three.
So I'm with you, people with low acid production can also have reflux. There is still a lot about
the digestive system that science doesn't know about
. Some researches believe that in some people, it can be an autoimmune response, which would explain why medications don't help some people (along with a host of other reasons).