Sure..
While at the orchid society meeting a couple months ago, some of the mebers were Ph bragging on their Di water, and citing their sources as "best". Di ph in plants being extremely important as ph's too low will immediately "burn" a plant root and why drinking rodi may not be so good for us. Once the ladies had left, my wifes good friend and I continued the conversation as I had just gotten our rodi kit. He is a scientist working in a lab and they produce di water ao different Ph as required in some testing . I believe he said around 5.6 at the lowest. they do this with more densely packed di resins to achieve this. one caution he gave us was to make sure we used the correct water pressure as the higher pressure on the resin replicated the dense packing of their di and can lower the ph, but really just make sure you shake the bottle or just let it set around and its likely fine. As I usually do let it set anyway it's not really a problem, and most who buy it have it poured into the bucket and drive it home its not a problem. But in several instances here in r2r ive seen who have quickly set up a hospital tank make fresh rodi and mix salt into it. Once the fish went in went down hill quick. weater that was the lack of oxygen in fresh rodi or PH I cant be sure, I usually just suggest shaking up the bucket or making sure there's an air stone.
with the number of occasions Ive seen this happen Im going for low oxygen. Low oxygen, low ph, despite chemical buffering as I would assume salt mixes are aiming at a 7ph nominally.
I kinda put it out of my head as he said I couldn't have any of his high test low ph stuff anyway unless I wanted to grow Himalayan orchids and I usually let my rodi set around and I have salt water mixed incase of emergency as well. Ill google it.
edit, yea here it is.. as it sets and get gassed it drops to 7.
http://puretecwater.com/downloads/relationship-between-ph-and-deionized-water.pdf