On the T-tanks like you have, I learned that taking that cap off was #1 a PITA, and #2, not really necessary. If you can refill the tank without removing the lid, you're better off. If you have a syringe or a needle-tipped bottle of some kind, try that. After you punch the hole, then just drip right down into the tank instead of removing the lid to refill. That will save the last three tanks you have...at least until you can get something else. The only thing that will work with the atomizer you have will be those tanks, so until you get a different atomizer/cartridge system, you need to figure out how to use those. I think popping the cap off of the tank weakens it, and causes it to leak.
I have syringes and needle-nosed bottles, but if you don't....here's a suggestion. Take a regular bottle with a dripper tip and either file it down with sandpaper, or "whittle" it down with a pocket knife so that the tip will fit into the little hole in the tank. Then never pop the top off of the tanks....