That looks like an Aspire C3? I think? I was just looking at them yesterday, was interested but I have plenty of better tanks so did not purchase.
Do you know the resistance of your coil? It should be printed on there in tiny letters, if your pen style device doesn't have adjustable wattage, you may be exceeding coil tolerances. I'm glad thinning your juice helped, but I'd suggest with whatever future setup you try, you get a battery that has adjustable wattages, if you can. There are lots of fairly inexpensive starter kits and some don't pair well together, while others are just great. I think the ego 1 mega is a great choice for a tank, or even a complete setup might be helpful to you. You can take your time and look around, but there are also a lot of labor day sales going on right now, not sure what part of the world you come from, though... and if you can import...
Best of luck and welcome to ECF!
Anna