Ok so I've been using the vivi nova and I actually like it. I've modified it in no way and it works just fine for me for the most part..... But I use a all vg juice that I add pg to in a 2 to 1 ratio. The juice is clear when it goes in, but at half a tank (even after I clean it) the juice turns golden brown and the taste changes. It doesn't taste bad even, but it does change (and I do like it better before it does). I can't for the life of me figure out why. The juice in question (in case it matters) is ultrapure from innovapor.