I have to ring in a put in a few words about the Vivi Nova. I used to have 5, though they were not the "best" they certainly were not the "worst" I would not recommend them to someone with out a few words of advise. They are rather hit or miss as an "out of the box" item. Though some are lucky enough to get them working as is, most have to be fiddled with to work at their full potential. If you look at all the threads and videos on youtube, they need some tinkering to get them to work,
The heads are mass produced, the tanks are mass produced and some come with flaws. The air intake usually needs some modding, I made the air holes slightly larger ( the ones at the 510 connection) the silica is worthless. The little white thing around the head , I take those out. You have to make sure that the head is on real tight or it opens up and leaks in
juice thru the center pole. If you are unlucky to get one that the threads are not perfect than they leak . Leakage from 510 connection is because the head is not on tight or you tipped it and juice went down the center. Sometimes when screwing on the top cap the little stopper on top of the head makes contact with the top cap and it loosens it and leaks. You have to keep them tipped and swish them as juice levels go down, or dry nasty taste. The little silicone cap around the head usually needs trimming to keep the wick from touching it, or you get the plastic taste. Then the legs or wires around the little grommet at the bottom of the head melts sometimes and again plastic taste.
Ok, I can go on with more quirks and fixes, I found them all on the numerous threads here in ECF. After all the fiddleing they are fantastic, even with their handicaps. I kept wanting to find something like the VN but better made and easier to set up and not have to worry about keeping it upright etc. I finally found it. I got an Odysseus, its all the VN wants to be , lasts for a lifetime, built like a russian tank, I know, its expensive, hard to find, but the solution is the Terminator. ITs not 100 % without a slight learning curve but its easier to set up than the VN. No leaks, vapes like a storm. It can use silica or cotton. Its more expensive than the VN but will out last it. Just a thought to make life easier.
After I got my Ody and then the Term, I sold all my VN, which were all modded and vaped just as good as the Ody and Term as far as flavour, but with out all the hassle and handicaps. Those that bought my VN were so lucky and they loved them compared to the ones they had.