i have a protank 2 , mini protank 2, 3 smok dct tanks and it seems that anything i try they leak on me its always when there half way full or if its a little lower. i now set them upside down when not using them and it seems to keep them from leaking out the bottom while sitting and not being used but if i go from inside my house to outside if its a little cold they seem to leak even faster is there anyway of fixing this problem ?