I have not tried the silicone caps but they sound like a good idea . I have had several type A and type B tanks and I have never had one leak yet so I can only guess at what the problem might be . I have stuck a tank on a needle plate that was taked out of an atomizer . The needle plate did not have a wick in it and it did not leak . You can hold a full tank upside down and unless you shake it it does not leak so you have to guess what will cause a leak . It has to be one of a couple of reasons . The eliquid is too thin either by heat or just being thin in the first place . A bad wick might be an issue if it is too small or maybe pushed down too far but is has be be drawing the eliquid out of the tank somehow . That is why my first guess is always that the tank has not been pushed down far enough and maybe when you draw you are drawing juice out of the hole and not through the wick .