I'll let Rocking Randle respond, but as far as I know, these tanks are polycarbonate plastic, and I would think easily food grade. However, they are not impervious to any juice. Those high citrus or high acid juices like melon, orange, and hot cinnamon will etch the tank and ruin it. Some other juice vendors will post a warning that certain juices are not to be used on plastic tanks.
Any Halo juice is perfectly safe in any Triton tank and the smaller mini tanks.
By the way, I see a lot of pg and vg liquids sold from other sites saying "food grade." This is a class lower than pharmaceutical grade. And Halo used pharma grade pg and vg in their liquids. Hence the name, "Halo Purity."